In the city of Futo, detective Shotaro Hidari has an unpleasant visit from his new boss Akiko Narumi, who has just arrived after learning that her father has gone missing. As Shotaro learns of the girl's relation to his mentor and boss, hiding what became of him, his childhood friend Marina Tsumura arrives in need of his help in finding her boyfriend Yousuke Togawa. Taking the case, with Akiko tailing him against his will, Shotaro learns from his best friend Detective Mikio Jinno that the Windscale building Yousuke worked at has been destroyed by a fiery Dopant. Akiko's initial curiosity turns into terror when she and Shotaro are attacked by the Magma Dopant. Later that night, staying in spite of being told to leave, Akiko ends up stumbling onto a secret room where she meets Shotaro's partner Philip before she unintentionally has him focus on takoyaki instead of the Dopant. As Shotaro explains what the Dopant are, Philip finally resumes his research as he accesses the Gaia Library to put the pieces together before Shotaro heads out. Shotaro finds Yousuke, approaching him to have him return to Marina. However, thinking he works for Windscale, Yousuke transforms into the Magma Dopant to attack Shotaro. He calls Philip, who uses the Cyclone Memory in his own belt, which travels with his soul (or in other words, Soul Forwards) to Shotaro's Double Driver, allowing him to transform into Kamen Rider Double. He battles the Magma Dopant as CycloneJoker before transforming into LunaJoker to use his limb-stretching powers to overpower the Dopant. Double then transforms back into CycloneJoker to execute the Joker Extreme, destroying the Magma Memory and returning Yousuke back to normal. However, before he can do anything else, Yousuke is taken by the T-Rex Dopant. Double summons the RevolGarry with Akiko and Philip's body inside.[1]

After using the Revolgarry to drive off the T-Rex Dopant, with Akiko learning about Kamen Rider Double's existence while trapped in the vehicle, Yousuke is later found dead with Shotaro forced to tell Marina about it. Seeking the truth behind Yousuke's death and uncover the other Dopant's identity, Shotaro goes to see his informant "Watcherman", making their way to the site of the Magma Dopant's previous attack where he learns that Yousuke and the person who became the T-Rex Dopant were partners in crime. With this knowledge, and finding an article of clothing after evading the T-Rex Dopant, Shotaro has Philip execute a search on the T-Rex Memory with the Windscale clothing line. Once Philip identifies the Dopant to be Marina, Shotaro takes the revelation hard and took offense to his partner's insulting his kindness towards the criminals. Turning in his Body Memories, Shotaro confronts Marina as she reveals that she was fired and wants revenge, attempting to get Shotaro's sympathy. When she realizes that Shotaro has already contacted the authorities, in spite of him telling her to just turn herself in, Marina becomes the T-Rex Dopant and attacks the police before chasing after Shotaro with intent to eat him. Philip arrives at the last second to save him as the two make their peace and transform into Kamen Rider Double to fight the T-Rex Dopant. Akiko takes Philip's body out of harm's way by hiding in a police car, but they are soon put in danger when the T-Rex Dopant assumes her Big T-Rex form with Double transforming into HeatJoker to fight her before dragging the car behind her. Chasing after them on the HardTurbuler, Kamen Rider Double transforms into HeatMetal to defeat the T-Rex Dopant before reassuming CycloneJoker to save Akiko and Marina, who is arrested soon after. While this chain of events occurs, the Gaia Memory dealer Kirihiko Sudo receives a Gaia Memory from the Sonozaki family as an engagement present.[2]

At the Narumi Detective Agency, Shotaro gets into another argument with Akiko over her cramping his style until Philip changes the station to the Healing Princess radio show hosted by Wakana Sonozaki as she mentions the rumored Million Colosseo casino during her Futo's Mystery Tour segment. By then, a couple who owns a pastry shop arrive to hire Shotaro to follow their daughter Yuko Izumi, who has been acting strange recently. Losing Yuko because of Akiko, Shotaro goes to Watcherman for answers, leading them to Goro Murasame who came from the Million Colosseo and lost everything. Leaving him to contact Philip, who freezes up upon the mention of the word "family," Murasame is attacked by the casino owner Taizo Kaga, the Money Dopant. Shotaro pursues the Dopant, but is forced to fight the monster on his own until Philip comes to and they form Kamen Rider Double. Transforming into HeatJoker and about to finish is opponent off, Double is hit from behind by a mysterious Dopant, covering the Money Dopant's escape. After getting an autograph of Wakana for Philip while searching for clue in the roads leading to it, Shotaro learns of a fake public bus that Yuko takes to the Million Colosseo, following close behind on his own. When he discovers Akiko in the bus, he is attacked once more by the Money Dopant, transforming into Kamen Rider Double and then assuming the form of CycloneMetal to fight the Dopant. However, the Dopant reveals his ace in his Life Coins as he unknowingly causes Philip to freeze up, leaving Shotaro to fend for himself as Akiko enters the Million Colosseo.[3]

After surviving the Money Dopant's attack, Shotaro gets a glimpse of Philip's family as the young man comes to and becomes crazed as he searches the Gaia Library for "My Family" only to find a book with the pages torn out. Shotaro attempts to put the worried Philip at ease until he gets a call from Akiko from the Million Colosseo. She uses the Bat Shot to broadcast Yuko's loss at the roulette wheel after she bet her life to win back her earnings, with the Money Dopant sealing the woman's soul into a Life Coin. When Akiko reveals herself to and nearly gets herself killed, Philip challenges the Money Dopant to a game of chance to save her and get the Life Coins, using his and Shotaro's Gaia Memories as collateral. While Philip researches on everything gambling related, Shotaro ruminates on the family he saw in Philip's memory before he and Philip board the bus to the Million Colosseo. Philip easily predicts the results of the roulette, winning most of the Life Coins until Kaga mentions the word "family", breaking Philip's winning streak and winning back his Life Coins along with most of the Gaia Memories. Tagging it for Philip, Shotaro then challenges Kaga to a winner takes all game of Old Maid. Though Kaga played Shotaro into a position where he can win, Shotaro turns the tables by using the Double Driver to link his mind with Philip's to win with his partner's abilities. Enraged, Kaga transforms into the Money Dopant and escapes as Double chases him down, assuming LunaJoker and LunaMetal to fight him. When the Money Dopant attempts to use the word "family" to make freeze Philip up again, he resolves that Shotaro and Akiko are family enough for him at the moment. Double transforms into HeatMetal and causes the Money Memory's Memory Break, freeing Yuko Izumi and everyone else from the Life Coins. On the radio later, Wakana Sonozaki mentions the newest mystery to hit Futo: Kamen Rider Double. Elsewhere, after being tested by Wakana as the ClayDoll Dopant to see if he is worthy of the Nasca Memory's power, Kirihiko's wedding to Saeko goes off without a hitch, and the new family pose for a photo together, all transformed into their Dopant forms.

At a press conference at the Futo Wind Power Laboratory, councilwoman Miyabi Kusuhara presents her designs for the construction of the Second Futo Tower. During her speech, a barrage of bullets rains down. Shotaro, who has been hired as Ms. Kusuhara's bodyguard after seeing she is being targeted by a Dopant, takes her out of harm's way before running off to transform into Kamen Rider Double in secret. Returning to protect Miyabi, Miyabi's daughter Asuka calls Double "papa" before he deflects the bullets as CycloneMetal. When the gunfire stops, Double goes to investigate where the bullets were coming from with the Dopant no where in sight. While Akiko delievers the bullet to Philip to study, Shotaro gets Ms. Kusuhara out of her apartment, the Dopant attacks again. Shotaro sends the Bat Shot out to do reconnaissance while making sure Ms. Kusuhara is not harmed. The next day, Shotaro escorts Miyabi and her entourage head towards the area of land needed to build the Second Futo Tower on. However, its owner Genzo Takamura refuses to let them through. As the group leaves, Kirihiko Sonozaki arrives to tell Takamura to get the job done. Later at the riverside, Ms. Kusuhara tells Shotaro that her husband Daizaburo was planning on building the Second Futo Tower when he was brutally murdered last year and that she has been lying about this fact to her daughter. At this time, Philip pieces together the clues and determines that the attacker is Takamura using the Anomalocaris Memory and attacks from the water. Upon realizing that Miyabi is in danger, Shotaro transforms into Kamen Rider Double and protects her just as the Dopant attacks, transforming into CycloneTrigger to end the bullet barrage and then using the Joker Extreme to break the Anomalocaris Memory. However, when he sees that the man is not Takamura but Takamura's friend and that the Gaia Memory is not the real Anomalocaris Memory (only a prototype model), the real Anomalocaris Dopant attacks just as Asuka runs towards Double, wanting to thank her "papa".[5]

After Asuka and her mother flee from the assassin's attempt, the Anomalocaris Dopant escapes with Kamen Rider Double unable to pursue. Still worried about Asuka's safety, Shotaro talks to Miyabi that it is not right for her to lie to her daughter. After talking to Asuka and realizing why her mother lied to her, Shotaro becomes conflicted on the matter and is not sure whether to tell her the truth about Double. The next day, after Akiko gets information for him from Watcherman and Santa-chan, Philip manages to uncover information about Asuka's father. During that time, after nearly telling Asuka the truth about her father, Shotaro is caught off guard when the Anomalocaris Dopant kidnaps Asuka. Surviving the fall, Double pursues the Anomalocaris Dopant using a tracker he placed on Asuka with the Spider Shock during his fall. However, he is attacked by the Nasca Dopant who wishes to confront the Kamen Rider one-on-one. Philip realizes that their foe has a Gaia Driver, and Double barely wins with an unorthdox move as HeatTrigger to blast the Nasca Dopant at point blank range. Their transformation is cancelled, leaving Philip unconscious as Shotaro follows his tracking beacon to Takamura's factory where Ms. Kusuhara makes her way to after receiving a text message from her daughter's kidnapper. By the time Akiko revives Philip with vinegar, Shotaro manages to find Asuka just as Miyabi is nearly killed by Takamura as the Anomalocaris Dopant. Kamen Rider Double saves her and assumes LunaTrigger to rescue Asuka before going after the Dopant as he assumes his Big Anomalocaris form. Summoning the RevolGarry, Double uses the HardSplasher to fight the Anomalocaris Dopant underwater and defeats him. Leaving Takamura for the police, Double bids Asuka farewell the way her father used to treat her. Meanwhile, Saeko apologizes to her father about their failed attempt to do away with Ms. Kusuhara, seeing Kamen Rider Double to be an even greater hindrance than expected with the weaklings working for her.

While doing some research in the Gaia Library, Philip comes across a locked book he cannot open titled "Heaven's Tornado", a street dance which leads him to Dango Inamoto. After realizing he cannot go any further without contacting a young man, Philip leaves the office to hunt him down with Akiko in tow. However after finding Dango and confronting him about Heaven's Tornado and showing his own dance moves, Dango refuses to tell Philip anything and leaves as the two follow to a public bus incognito. Shotaro, meanwhile, goes to investigate Kazehana High School after a note tied to a rock flies into the window prior to Philip's going out. After being confronted by the school's security, he runs to the principal when attacked by the Cockroach Dopant, calling Philip to transform into Kamen Rider Double. The Cockroach Dopant is nearly defeated after the two transform into LunaTrigger until Akiko sends the Stag Phone to tell Philip that Dango is getting off of the bus, allowing the Dopant to escape as Double gets into an internal argument. When Dango arrives to Kazehana High, he begins dancing to call out Chizuru Hoshino, his former dance partner, a fact that Philip takes into account when Dango's boombox is shut off by a teacher and the boy runs off in search of Chizuru. As Philip and Akiko follow Dango to the school's pool, they are suddenly attacked by the Smilodon Dopant who is out to capture Philip. Elsewhere, Shotaro meets with his high school informants Queen and Elizabeth, who show to him that the Cockroach Dopant's attacks are related to the "Dark Bug Exterminator" website and that the principal is not the intended target but Chizuru. Shotaro returns to Kazehana High, meeting with Dango just as Chizuru is attacked by the Cockroach Dopant who reveals that it was Dango who posted her name on the website. However, before Shotaro can transform into Double, Philip and Akiko have to escape from the Smilodon Dopant by jumping off of an overpass into a garbage truck. Once more, Kamen Rider Double LunaTrigger has the Cockroach Dopant in his sights when he is distracted by Dango and Chizuru fighting, giving the Cockroach Dopant the opportunity to steal the Luna and Trigger Memories right out of the Double Driver.

Losing the Luna and Trigger Memories, Kamen Rider Double is at a severe disadvantage against the Cockroach Dopant who man handles Double with his speed. Though Double uses HeatMetal to turn the tables, he loses the Heat and Metal Memories as well. Later, brought to the Narumi Agency by Shotaro, Dango reveals he was the one who threw the rock and that he posted on the Dark Big Extermination out of venting his rage when he and Chizuru broke up as she joined the swimming team without explaining herself. As Philip looks up Chizuru's reason through the Gaia Library, Shotaro meets up with Santa-chan for information about Cockroach Dopant, giving him a self-published manga that leads him to dōjinshi artist Ikari. Ikari speaks to Kirihiko on the phone, informing him of his possession of Double's Gaia Memories before taking the man's advice to take the remaining Gaia Memories and Double Driver for his own use. Shotaro confronts Ikari, seeking to retrieve the Gaia Memories until Ikari transforms into the Cockroach Dopant and escapes. Shotaro sends the Stag Phone to track him, but the Cockroach Dopant manages to ground it. Meanwhile, Philip finds Chizuru and brings her back to the office to force her and Dango into the RevolGarry so they can make amends. Though the two argue, Chizuru reveals to Dango that she only took up swimming to perfect her dancing and that she still shares his dream of becoming a great dance team. As they leave so Philip can watch Heaven's Tornado, Akiko receives a phone call from Shotaro's phone and tells him where they are going. However, the Cockroach Dopant is on the other line and shows up to break Chizuru's leg. Dango tries to fight him off as Philip interrogates Chizuru on the keyword for Heaven's Tornado: "Wave". With all of the knowledge of the dance at his disposal, when Shotaro finally arrives to fight the Cockroach Dopant as Kamen Rider Double, Philip uses his newly found dancing abilities with Dango to fight. They use Heaven's Tornado to attack the Cockroach Dopant, retrieving the Gaia Memories and transforming into LunaTrigger to deliver the final blow and leave Ikari for the police. Back at the office, Akiko shows Philip a thank you note from Dango and Chizuru inviting them to see their next dance performance, believing that he has changed from his experience. To Akiko's dismay, Philip throws out the note and expresses an intense desire to see Mount Fuji after reading about it in his books.

After Akiko has another argument with Shotaro over the amassing bills, five clients appear all stating that their loved ones have all disappeared, and that they are all pâtissiers. One client, pâtissière Mai Asakawa, is searching for her father Yuzo Asakawa, who was last seen working as the pâtissier for the Sonozaki estate. After Philip discovers that all five pâtissiers also worked at the Sonozaki estate, Akiko goes undercover as a maid to investigate the denizens the mansion and keep an eye on Mai, who is now working as the mansion's new pâtissière. Shotaro, furious, tries to talk her out of it, and nearly tells her what had happened to her father, but finds himself unable to tell her the events of Begins Night, blaming himself for his boss's death. As Shotaro tries to sneak into the mansion, he encounters Kirihiko, believing him to another stalker of Wakana's. Elsewhere, Mai is suddenly attacked by a living whipped cream, alerting Shotaro and Kirihiko. Shotaro enters the grounds and transforms into Kamen Rider Double, saving Mai and discovering the culprit is the Sweets Dopant. Double is coated in the cream which hardens like concrete until he transforms into CycloneMetal and summons the Bat Shot to form the Sonic Shaft to free him. When Kirihiko discovers Kamen Rider Double is on the grounds, he transforms into the Nasca Dopant and enters the brawl. Elsewhere, inside the mansion, Akiko trails Ryubee Sonozaki but he apparently disappears from her sight, allowing him to transform into the Terror Dopant to deal with the disruption outside his estate.

The three-way battle between Kamen Rider Double, the Nasca Dopant, and the Sweets Dopant is suddenly halted by the presence of the Terror Dopant. All three barely escape the attack, and Shotaro, feeling the full effects of the Terror Dopant's fear inducing powers, believes Akiko is in danger. After Akiko tends to Mai Asakawa, she admits fault in leaving her alone as Shotaro tells Akiko about her father's ideology, only to find she ran off as he was about to tell her what happened. Shotaro follows her to the Futo Museum where she talks to Ryubee, noticing the magma, anomalocaris, and Tyrannosaurus exhibits as he recalls the Dopants he fought previously before having an unnerving encounter with Ryubee. Later, at the Sonozaki family's afternoon tea, Akiko reveals her identity as a detective to reveal who has been attacking the pâtissiers. She accuses the overweight maid Fukumi Shirotsuka because of her sweet tooth when Philip comes across the true culprit. The maid Yukiko Sasaki suddenly recoils in disgust, having eaten a pastry prepared by Akiko that she finds disgusting, transforming into the Sweets Dopant to kidnap Mai and Akiko. Shotaro, having been watching from the window outside, transforms into Kamen Rider Double to give chase as Kirihiko and Saeko witness him transform. Both assume to their Dopant forms and halt Double to deal with him for his meddling in their affairs. At Yukiko's hideout, she reveals her motives for the kidnappings before she attempts to kill Akiko for the pastry she made. Kamen Rider Double tries to escape the two powerful Dopants, gaining the upper hand when the RevolGarry arrives and he escapes on the HardBoilder Start Dash Mode, using the break away boosters to escape from the Nasca Dopant, who is struck by one of the Taboo Dopant's plasma spheres for failing to catch Double. Just as Akiko is about to be killed, Double arrives to save them only to see Akiko express the same conviction to protect a client as her father had. Kamen Rider Double fights the Sweets Dopant in HeatJoker form, using the Bat Shot's Luna Maximum Drive to pinpoint the Dopant's location before executing a Memory Break with Joker Grenade. Back at the office, as Akiko has Philip taste the pastry she made, Shotaro decides to hold off on telling her of the events of Begins Night.

At the Narumi Detective Agency, Akiko has fallen ill with a cold and calls Shotaro an "idiot who never catches a cold", spurning Philip's interest in this phrase despite not knowing that it is an idiom. The agency then gets a phone call from a man named Mikio Aoki who claims that he is being chased and needs help. When Shotaro arrives on the scene, he comes across the man before seeing a black SUV run through him, causing the man to writhe in pain before falling down dead. When Shotaro is taken in for questioning at the police station the next day, Makura thinking that he murdered Aoki, Jinno arrives to reveal that Aoki died from a mysterious disease. Deciding to get to the bottom of it, Shotaro learns from Watcherman that Aoki was a member in a chop shop street gang. They head to the gang's usual hangout to talk to its leader Kurosu. Shotaro questions him, until Kurosu pulls a gun on Shotaro after one member of his posse hints that the SUV was stolen. Akiko, scared for their lives, drags Shotaro out before the other two gang members leave and talk about checking out the SUV. Shotaro trails them as the SUV appears once more to run down the other two members, killing one of them before chasing after the other. Shotaro contacts Philip to transform as Philip is still investigating the idiom. Shotaro instead activates the Bat Shot to take photos of the driver, eventually transforming into Kamen Rider Double to save the younger gang member before the Nasca Dopant intervenes. This allows the SUV to run down the gang member. Later, Philip identifies the driver as Kōhei Yamamura, whose older sister Sachi Yamamura was hit by a car driven by Kurosu's gang and is currently in the hospital in a coma. Believing that Kōhei is the Dopant, Shotaro confronts him and accuses him of it. Kōhei runs off into a bus to escape to continue his revenge, succeeding because Sachi's fiance Noriyuki Yushima just got off the bus and holds Shotaro at bay. After talking to Yushima and learning about Kōhei, Shotaro gets a call from Akiko that she has followed Kurosu to a warehouse so he can gun down Kōhei in the SUV. Kamen Rider Double arrives at the warehouse on the HardBoilder, provoking Kōhei to chase after him. Assuming HeatMetal and using the RevolGarry, Double manages to wreck the SUV without being infected. While inspecting the wreckage with Akiko, they cannot find a Gaia Memory just as the real Virus Dopant makes itself known.

Revealing itself, the Virus Dopant kills Kurosu as Kamen Rider Double is powerless to keep the monster from running away as Shotaro senses sadness from it. The next day, after reviewing the how the hit and run on Sachi began the Virus Dopant's attack, Shotaro believes that Yushima is actually the Dopant. Heading to a girl school where Yushima teaches art, Shotaro finds the Virus Dopant attacking Yushima. Double saves Yushima and fights the Dopant before it runs away. Back to square one, Akiko believes that Sachi may be the guilty party. Though Shotaro could not believe it, Akiko and Philip visit the hospital where Sachi is being kept and he finds her Living Connector. Philip concludes that the Virus Dopant is formed from Sachi's consciousness, and seeks to contact her through the Gaia Library. Upon meeting her, she tells Philip that just before she received the Virus Memory, she caught Yushima proposing to another woman. Elsewhere, Shotaro learns from Queen and Elizabeth that Yushima is a casanova who uses women for his art. When Shotaro goes to confront him, he arrives just as the Virus Dopant is about to kill Yushima. Shotaro begs the monster to stop while he forces Yushima to apologize to Sachi. Neither Shotaro nor Philip can reason with Sachi, leading the powers of the Virus Dopant to take over, forcing them to transform into Kamen Rider Double to fight the Virus Dopant. After Philip realizes that the only way to defeat the Dopant is to completely destroy it, Shotaro decides that they transform into HeatTrigger and use the Trigger Explosion Maximum Drive to deal the deathblow. The Virus Dopant is vaporized and the Virus Memory is ejected from Sachi's body and breaks. Soon after, Shotaro punches Yushima for causing the deaths of the four gang members by breaking Sachi's heart. A few days later while closing the case, Shotaro begins showing symptoms of a cold

After Wakana Sonozaki deals with a stalker Gaia Memory dealer who attempts to force her to marry him, Wakana airs the debut of her song "Naturally" before receiving a call from a "Mister Question" who wants to give her a present. A nearby building is destroyed by the Violence Dopant soon after. Arriving as Wind Wave DJ Motoko Saeki diverts press attention away from Wakana over the incident, Shotaro sneaks by and offers his services to her, though she refuses. Later at the Sonozaki mansion, Wakana fights with Saeko over her quitting her job at Wind Wave and going into the family business. Though Ryubee stops the two from fighting, he agrees with Saeko and Wakana promises to handle things. The next day, the police and Shotaro investigate as Mister Question calls Wakana again. On Philip's suggestion, Shotaro talks to Mister Question himself so he can deduce the Dopant's goal. Philip confirms the location to be a nearby amusement park where the Violence Dopant is igniting the gas main. When Shotaro shows up and transforms, he is easily outmatched. Later that night, while the crew is investigating, Wakana storms into the agency, scaring Shotaro and Akiko temporarily out of their wits, to find Philip as he hides in the hangar. Keeping the door closed, Philip explains that Mister Question used an interview where Wakana mentioned her love for aromatic candles and yearly visits to the amusement park to set up his attack. Impressed, Wakana forces the door open slightly, grabbing Philip's hand to thank him, but stimulates his memories as he promises to help her. The next day, Wakana allows Shotaro to accompany her to a special recording at the Izumi family's pastry shop. During the show, the shop is called by Mister Question stating his intent for Wakana to always see her favorite scenery, which Philip figures out is the destruction of Futo Building #3 that obstructs the view of the Futo Tower from Wakana's bedroom. Shotaro heads there, now able to fight him as Kamen Rider Double HeatMetal. However, the fight is interrupted by the ClayDoll Dopant who attacks Double, while Kirihiko watches unnoticed by the sidelines. During the fight, Double and the ClayDoll Dopant come in contact, triggering the same reaction Philip had before when Wakana touched his hand. As Philip tries to figure out what this all means, the Violence Dopant enters the fray once more as the Violence Ball, shocking Double and Kirihiko by landing on top of the ClayDoll Dopant and shattering her into thousands of pieces.

When the Violence Dopant runs off after crushing the ClayDoll Dopant, Kamen Rider Double prepares to give chase until the ClayDoll Dopant reforms and walks off. Later, Wakana visits the Asakawa family's bakery for her show. However, Mister Question calls the bakery and tells her that he has an amazing present--and gives no hints. Using what they know about him, Philip states that Mister Question is someone Wakana knows. Sneaking out, Wakana visits Philip as he learns of her family's past; her sister Saeko would take out the anger she had towards their father on Wakana, and their younger brother would help Wakana cope with the anger she had towards her sister, almost acting as her conscience. While this occurs, Motoko arrives to take her place in reviewing the Fumen ramen stand's products. With Wakana's help, Philip is able to deduce Mister Question's identity. After Philip promises to see her once this case is solved, Wakana makes her way to the Fumen ramen stand, and Philip's curiosity starts to get the best of him. After Wakana finishes the show, Mister Question calls, and Wakana reveals him as her manager Tsuyoshi Ageo, who walks up and assumes his Dopant form. He abducts Wakana, and Shotaro calls upon Philip as he resists reading a Gaia Library book about Wakana. Double chases the Violence Dopant on the HardTurbuler, until assuming LunaTrigger and catching him in a net projected by the Trigger Magnum and Spider Shock. When freed, Wakana asks Ageo where he received the Gaia Memory. After professing his love for Wakana, he admits the Gaia Memory was a gift from someone else and runs off with Kamen Rider Double in pursuit. Wakana goes to the Wind Wave studios, confronting Motoko who admits that she bought the Violence Memory and used Ageo to get rid of her as competition. Infuriated, Wakana becomes the ClayDoll Dopant to kill her, only to stop after remembing what both her younger brother and Philip told her. Taking advantage of Wakana's mercy as she leaves, Motoko decides to expose her on the air until Kirihiko arrives, becoming the Nasca Dopant to permanently silence Motoko. Elsewhere, Kamen Rider Double has defeated the Violence Dopant with a Trigger Stag Burst, dropping Ageo off on a rooftop once the Memory Break completes. Later, perplexed by her knowledge of Gaia Memories, Philip calls Wakana to asks her if she has a Gaia Memory as she reminds him of their promise. After asking her to wait a bit longer for their meeting, Wakana discards the ClayDoll Memory on the mansion's patio and walks away, only for Ryubee to pick it up moments later

After finding Philip trying to train like a boxer through weight-loss hell tactics in the RevolGarry's cockpit after listening to Wakana, seeing a tiny dinosaur robot from his past, the Narumi Detective Agency gets a new client named Fuyumi Aso who ask them to find a Kamen Rider. Thinking it was easy, they learn that the "Kamen Rider" is actually an impostor who has gone on a crime spree and Shotaro takes the case to get to the bottom of it after learning more at the site of culprit's robbery on an armored truck. Using the Bat Shot, Shotaro finds the culprit Dopant riding a motorcycle to attack the next armored truck and he arrives as Kamen Rider Double in time to stop the attack as the Arms Dopant flees from the scene. After losing the Arms Dopant, Double finds a small scrap of metal behind. Later, Akiko and Shotaro confront Fuyumi about her connection to the Dopant and she reveals that she is one half of the Twin Rose cat burglar team, and her partner Kenji Kurata is the Arms Dopant. Despite being lied to, Shotaro still accepts the case on the condition that Fuyumi turns herself in. As Shotaro explains to Akiko his personal reasons for going after the Arms Dopant, Philip has trouble searching for Kurata's hideout until Akiko identifies the piece of metal as being part of an apple-shape, leading him to the Sherwood Building. As Shotaro makes his way there, Philip is still troubled by the mystery of why Kurata is pretending to be a Kamen Rider. With Akiko and Fuyumi, Shotaro confronts Kurata and orders him to discard the Arms Memory. Kurata, under the Gaia Memory's influence, refuses to give it up and transforms into the Arms Dopant to face him. Shotaro transforms into Kamen Rider Double and fights the Arms Dopant, until the Dopant gets a call from his client who tells him to spring the trap. The Arms Dopant calls upon a small army of Masquerade Dopants who have captured Akiko and Fuyumi, threatening to kill the former if Double does not revert. Shotaro follows through, while keeping in mental contact with Philip to prepare the Luna Memory, but the Arms Dopant fires a bullet that closes up the right side of Shotaro's Double Driver once the Heat Memory is removed. After the Arms Dopant reveals his target to be Philip, Shotaro yells at him to run as he staggers out of hiding from the RevolGarry. Managing to dodge fire by the Masquerade Dopants, Philip runs outside where he comes across Saeko, the one who set up the trap. With open arms, Saeko walks towards Philip, and calls him Raito, the "Chosen Child".

When confronted by Saeko and learning his true name, Philip refuses to go with her as she assumes her Dopant form to take him by force. After resisting temption from the Fang Memory, Philip manages to escape with the RevolGarry, forced to leave Shotaro and Akiko in the hands of the Arms Dopant as he loses consciousness. While Philip wakes up in the base later, he receives a call from Kurata to comes to the Tsubasa district and surrender or else he'll kill Shotaro. Philip contemplates a way to save Shotaro, driving off the Fang Memory until he is visited by Watcherman and Santa-chan, both looking for Shotaro, and Detective Makura, who learned of Fuyumi's visit to the agency. Learning she was released, Philip saves Fuyumi from the police as he needs answers. Though he's no longer the Kenji she knew, Fuyumi refuses to give up on her partner, giving Philip the final resolve to save Shotaro as he runs into the Fang Memory. Elsewhere, a bound Shotaro and Akiko discuss their means of escape, and Shotaro says that only their seventh Gaia Memory, the living Fang Memory, would help, but its last use was too taxing on Philip's mind and body. The next day, with Saeko watching from afar, the Arms Dopant forces Akiko to hold Shotaro over a set of spikes by rope and pulley, and just as she is to lose her grip, Shotaro is saved by the Fang Memory and Philip's arrival where he transforms into Kamen Rider Double FangJoker against Shotaro's pleas. With Philip unable to control himself, Double goes into a berserk rage attacking the Masquerade Dopants until only the Arms Dopant holding Akiko hostage is left in an attempt to get Double to stop. Just before he is to slash Akiko, Shotaro manages to find Philip within the burning Gaia Library and snap him out of the berserk rage and bring the Gaia Library back to normal. Now in control, the two finish the battle and destroy the Arms Dopant with the Fang Streiser Maximum Drive, shattering the Arms Memory. Seeing Saeko drive off, with Philip's body no longer able to continue, Shotaro takes over as Double gives chase, assuming LunaTrigger to finish her off. However, the Nazca Dopant saves the Taboo Dopant at the last second with his newly mastered super speed. After saving a little girl as HeatMetal in front of Jinno and the police force, the Kamen Rider's reputation is saved and they return home. After closing the case, though Shotaro worries that the Fang Memory's resurfacing is a prelude to things to come, Akiko calls to Shotaro as Philip has decided to put on weight, to disastrous results, while the Fang Memory encounters a strange blue beetle-like device.[

During a visit to the Barber Kaze barbershop for a shace, Shotaro unknowingly comes across Kirihiko who is also there and reveals that he invented the city's mascot: Futo-kun. However, when they realized who each other was after the hot towels are removed, the two take it outside as they proceed outside for a fight, though Philip is unable to find the Fang Memory for Shotaro to use. The Nasca Dopant nearly has the advantage against Kamen Rider Double but stopped when the owner of Barber Kaze calls for Shotaro who has actually called upon him to find his daughter Akane who has gone missing for a few days. Shotaro agrees and returns to Agency, finding it in shambles with traps laid by Philip, who is obsessed with finding the Fang Memory until Akiko puts on Wakana's show where she talks about a strange birdman that catches his attention. After seeing Queen and Elizabeth for information, Shotaro learns that Akane has been hanging out with a bad crowd underneath the freeway bridge. When Shotaro and Akiko find them, Akane's friend Toma pulls out the Bird Memory, which he then passes to his friend Yuichi who transforms into the Bird Dopant. Shotaro prepares to transform into Kamen Rider Double, but Philip has claimed he found a rhinoceros beetle in his trap and Shotaro says that it is the wrong season for those. Shotaro manages to transform in time and give the Bird Dopant a beating as Luna Metal until Yuichi gives up and takes it out. However, before Double can take the Gaia Memory, it is thrown back to Toma who transforms into the Bird Dopant and takes Akane away as Yuichi begins writhing in pain. Watching the entire fight, Kirihiko confronts Saeko about the Gaia Memory being used by children, assured that the matter will be dealt with as she asks how his body is doing. At the hospital, Shotaro talks to Yayoi who says that Toma got the Bird Memory and they have been using it for fun until Toma decided to attack people. They learn his next target is the Fumen Ramen as Akane attempted to get them to leave, but Shotaro intervene before anyone can get hurt as the others runs off. Before he can transform, Philip shows up and says that he has discovered how the Fang Memory works by putting himself in danger and allowing it to arrive. They transform into FangJoker and manage to defeat him and cause the Gaia Memory to eject and Toma begins writhing in pain. However, it does not break, as Kirihiko reveals that the Bird Memory has more than one person using it, provoking Double to demand why he sold it to children. Though he has no idea how this could happen, the Nasca Dopant uses this opportunity to fight Double FangJoker.

The Nasca Dopant and Kamen Rider Double FangJoker fight, and the Nasca Dopant has the upper hand with his newfound super speed powers until he suddenly falls in pain. Philip is ready to deliver the finishing blow until Shotaro stops him, saying that killing him would not be right, citing the Futo-kun poster on a nearby wall and Kirihiko's love of Futo as a reason. Double and the Nasca Dopant end the fight and go their separate ways as Shotaro takes Toma to the hospital. Later at the Agency, as Akane blames herself for Toma, Philip returns from the Gaia Library and reveals the real Living Connector on Akane. She tells them that after she was having problems completing the high jump at school in preparation for an event, a woman approached her and gave her the Bird Memory to help. Later, as Akane rests, Shotaro leaves to contact Akane's father that they have found her. However, Akane wakes up and attacks Philip and Akiko in a withdrawal rage before running off with one of the Spider Shock's trackers attached on her. Akane returns to the school where she comes across Saeko, the woman who had given her the Living Connector in the first place, and the Bird Memory is returned to Akane. At the Sonozaki Family mansion, after seeing Saeko coming out of a secret doorway, Kirihiko enters it and finds himself in an underground cave system with a strange piece of equipment within it. Ryubee reveals it to be the source for the first set the Gaia Memories and the center of the Museum. Furthermore, Kirihiko learns that Ryubee intentionally allowed the Bird Memory to be given to children to test the new Gaia Memory's power, regardless of the consequences. An enraged Kirihiko threatens to kill Ryubee as the Nazca Dopant unless he is told how to defeat the Dopant without harming the child. But once he learned the answer, he begins writhing in pain as Ryubee explains that because he is also used to test the Nasca Memory's powers, revealing that its Level Two power is slowly killing him. Ryubee then transforms into the Terror Dopant to put him out of his misery as the Nasca Dopant escapes to only be chased by the Smilodon Dopant. But Wakana arrives and turns into the ClayDoll Dopant to save Kirihiko. Kirihiko thanks Wakana as she tells him to be true to himself, leaving to help the Kamen Rider with the knowledge he gained. By that time, Shotaro finds Akane just as she uses the Bird Memory and flies away. Shotaro and Philip transform to give chase, eventually summoning the RevolGarry to use the HardTurbuler to chase her in the air. During the fight with the Bird Dopant, she evolves into a stronger form and knocks Kamen Rider Double out of the HardTurbuler. Double changes into CycloneTrigger and tries to hold off the attacks until the Nasca Dopant appears to help by knocking the Bird Dopant out of the air and reveal its weak point with his Driver. Akane is freed after the Trigger Bat Shooting and the Nasca Dopant regresses into a pain stricken Kirihiko as reveals Museum's existence to Double before giving him his Futo-kun keychain and leaves. Later, Kirihiko calls Saeko and asks if she would leave town with him out of love. Saeko, in response, transforms into the Taboo Dopant and blasts him with one of her energy balls, taking the Nasca Memory and saying that she has bigger plans for the Gaia Memories. As she leaves, Kirihiko feels the breeze and disappears into a cloud of dust that drifts away in the wind. Days later at the Narumi Detective Agency, Shotaro opines on case's aftermath while looking at a newspaper covering Kirihiko's mysterious death. Suddenly, Akiko exclaims that a rhinoceros beetle is in the building and Philip asks where it is as it flies out the window. It flies to the police station where a man in a red jacket takes it and states his contempt for Futo while holding a red Rider-type Gaia Memory: the Accel Memory.

While down in the billiard hall below his office, Shotaro is approached by a man dressed in red who is in need of his services. Introducing himself as Superintendent Ryu Terui, he requests Shotaro's aid in investigating a crime wave involving frozen victims which may be connected to a Dopant. Though Shotaro turns him down, Akiko gladly accepts the case on his behalf after getting the payment in advance, forcing him to follow Ryu to a recent crime scene while Philip expresses an interest in Ryu. At the crime scene, the apartment of survivor Shinya Ikeda, Ryu finds a blue flower at the scene while Shotaro gets the low down on him from Jinno and Makura. After being manhandled by Ryu for being curious about the flower, Shotaro accompanies him to the hospital where Shinya is being held after his brush with death, finding him being attacked by a mysterious icy Dopant. Shotaro is about to transform when Ryu retrieves a large (and very heavy) sword –the Engine Blade– which he barely swings at the Dopant while ordering Shotaro to become a Kamen Rider, much to Shotaro's surprise. Shotaro prepares to transform, but is delayed due to Philip's latest research topic. After enough nudging from Shotaro, Kamen Rider Double is formed as he fights the icy Dopant, assuming HeatJoker to counter the Dopant's ice attacks. As Ryu gives chase, he sees a woman running off with a blue flower left behind. They return to the agency offices where Ryu enters the hangar much to Akiko's surprise, with Shotaro mortified to find Philip pretending to be a St. Bernard thanks to the latest Wakana's Healing Princess. Ryu reveals that he has been spying on them with the Beetle Phone the entire time and then reveals his Accel Memory and his intent to become a Kamen Rider. Though annoyed, Philip uses the Gaia Library to point Ryu to florist Makiko Katahira with Akiko's help. Shotaro, Ryu, and Akiko go to her flower shop where they encounter her son Kiyoshi who tells them that she spends her time at the Futo-En amusement park. Upon their arrival, as Shotaro and Akiko go off to find Makiko, Ryu meets with the mysterious woman Shroud as she gives him the Accel Driver (in a metal suitcase surrounded by a ring of fire.). Once Shotaro and Akiko confront Makiko about the icy Dopant's attacks, she runs off as the icy Dopant appears once more to attack Shotaro. Assuming HeatJoker for the advantage, Double is outmatched by the Dopant even after assuming HeatMetal. By then, Ryu arrives and activates the Accel Driver with his Accel Memory, transforming into Kamen Rider Accel. Now able to use the Engine Blade without being burdened by its weight, Accel uses it to overpower the icy Dopant as it attempts to escape. However, Accel assumes Bike Form to pursue before executing his Maximum Drive, the Accel Glanzer Rider Kick, on the Dopant. However, the icy Dopant shatters with no Gaia Memory in sight. They then see the real icy Dopant trying to escape, and when they follow it they see Makiko grasping a Gaia Memory. Kamen Rider Accel, infuriated for some reason, prepares to attack her, while Shotaro exclaims that Ryu should not attack an untransformed human.[

Just as Kamen Rider Accel prepares to attack Makiko, Kamen Rider Double HeatMetal intervenes allowing Makiko to escape. Enraged that Double's getting his way of executing owner of the W Gaia Memory, Accel forces him to revert and was about to kill Shotaro for his ideology until Akiko stops him. Ryu leaves after admitting that he hates Futo and sees no good in it. As Shotaro refuses to accept Ryu's ideology and heads out, Philip decides to investigate Ryu's relation to the W Gaia Memory in the Gaia Library. While Ryu follows Kiyoshi to his mother, Shotaro goes to see Watcherman for information on Makiko. Shotaro arrives just as Accel is about to kill her with Philip helping her escape. Forming Kamen Rider Double FangJoker, Philip manages to subdue Accel before revealing he knows about Ryu's family being killed by a Dopant with icy powers. Enraged that his past is revealed, Philip asks Ryu to tell him what had happened. Ryu tells how his father, before he died, told him that his family's murderer was a man with a Gaia Memory with the letter W. Ryu met Shroud soon after, receiving the Accel Memory and Engine Blade to get his revenge. Before he walks off to find Makiko, Shotaro informs him that she is not the Dopant. Taking Ryu to a dance club, Shotaro reveals Kiyoshi to be the icy Dopant and that his mother has only been protecting him. Suddenly, Makiko arrives, pleading for Kiyoshi to stop, but he shoves her off and escapes as the icy Dopant. After telling Makiko not to burden herself, Shotaro and Philip give chase as Ryu begins to contemplate how Shotaro kept him from making a big mistake. As HeatJoker and then HeatTrigger, Kamen Rider Double has trouble with the icy Dopant's abilities and is overwhelmed until Ryu appears once more and transforms into Kamen Rider Accel. Using the Engine Memory's Steam abilities in the Engine Blade, Accel deflects the Dopant's attacks before using a Maximum Drive to expel the Gaia Memory from Kiyoshi. After nearly giving Shotaro and Makiko a fright, everyone is surprised as Ryu slaps handcuffs on Kiyoshi instead of attacking him, stating that he will play by Shotaro's rules while in Futo. As Makiko comforts her son, Ryu picks up the Gaia Memory and realizes that it is the IceAge Memory, and not the W Memory. Elsewhere, now under Saeko's wing as she is being forced into the family business, Wakana is introduced to their family's benefactor and a high ranking member of the Museum. Wakana states that the man, though well-mannered, instills more fear in her than her own father. Saeko explains that the man is a brutal figure responsible for the crime wave of frozen victims. The man sits down at a piano and begins playing, until he retrieves a black Gaia Memory from his pocket: the Weather Memory.