Teropterids are evil beasts which pose as humans and live only to drink human blood. Fortunately for the human world there are groups dedicated to destroying them. A brooding and mysterious girl named Saya is the best teropterid slayer there is, and now, in 1960's Japan, she is sent to a U. S. army base which may be infested...
Saya leads a happy life with her adoptive parent, George, and brothers, Kai and Riku in Okinawa, Japan. She lost her memory and cannot remember anything beyond the past year of her life. After witnessing a creature kill a teacher at her school things automatically change. Now the monster is after her and the only one that can help her is a mysterious cellist. Now her true destiny begins to emerge and her life is changed forever.
After being kissed and being forced to drink blood, by the cellist, Saya's eyes begin to glow and she becomes a fighting machine. After easily slicing through the Chiropteran Saya collapses. She wakes in the hospital and hears George and David talking about her. Their conversation scares her so bad that she runs away. Now it is up to Kai to find her.
David has given George a deadline to hand over Saya back to the Red Shield. George takes Saya to his family grave to show what exactly happened to her one year ago.
George is taken into ICU after being severely injured. Angered, Kai takes the gun that George had been hiding and goes after Forrest. Riku informs Saya about Kai and both of them go off to search for Kai. Kai finds Forrest, but it seems he has become the monster he was when he attacked George. Now Saya must get to Kai as quickly as possible, for it is a matter of life and death. Can she get there is time?
David prepares his group to go after George. When they learn he has been secretly transfered to the Yanabaru laboratory in Northern Okinawa, they prepare to head there. When Kai finds out he decides he decides he want to go with the group. But will David allow it?
David, Saya, and Hagi infiltrate the Yanbaru laboratory to rescue George. While they are there David finds out the US army is artificially creating Chiropterans. Along with the information on the artificial Chriopterans, David finds the mysterious keyword "Delta 67". Meanwhile the Commander of US Forces on Okinawa has authorized surgical bombing of Yanbaru to remove any incriminating evidence.
While David and Julia decode what they found at Yanbaru, Riku finds out about George's death. After finding out, Riku hides in his room and refuses to come out. Now Kai must take on a fatherly role to cheer his brother up.
Saya is enrolled in a French school in Vietnam that was associated with the wine found at the military base, while Hagi goes undercover as a gardener. Not long after getting there Saya learns from her talkative roommate that the phantom at the school kidnaps girls that look similar to Saya. After investigating some more Saya is led to the bell tower where she comes face to face with the phantom.
Saya reports to Red Sheild that all the missing girls have similar looks to her. Meanwhile Riku meets a Vietnamese girl named Mui who has the same ability as him. After spending some time with Mui, Riku realizes the importance of his family and decides to try and reunite with Kai and Saya. The American military team makes it seem impossible when they kidnap Riku and Mui.
When Saya arrives in her class one morning, she finds a blue rose. With the blue rose in hand Saya and Haji go to the rose garden where the blue roses are said to bloom. After a little looking around they find a staircase leading underground in a shack. Is this where the phantom is hiding?
A ball is held once a year at the school and students and their parents arrive dressed in formal attire. Saya goes wearing a dress she borrowed from Min. While she is at the ball Saya meets a young man named Solomon. David and other people from Red Sheild show at the ball, but they are not the only strangers there. The Phantom appears and now Saya and everyone must do their best to defeat him.
Saya and the group, joined along by The Red Shield, Clara, Spencer, Rogers and McCoy, pursue the container carrying Diva which was transferred to the school. They trek up the Mekong River to the experiment farm of Cinq Fleche Pharmaceutical where they find Mui, Riku and Kai as well as numerous children kidnapped and brought here from all over Vietnam. Saya and the others are not aware of this fact, however, as they prepare for a clash.
Still held up at the experiment farm and surrounded by Chiropteran children, Saya soon hears mysterious humming and the roars of the Chiropterans. Eventually, the smell of blood becomes asphyxiating, and threatens to wrest control of herself from her.
Saya and the others briefly return to Okinawa for a day of rest from all the excitement. The Otanashi’s bury George's memento in the family grave, and Saya gets a chance to catch up with her best friend, Kaori.
Okamura, the reported from the newspaper, wants to find Saya so he can understand what happened at the wine barrel storage at the school. Meanwhile Mao is getting tired of not seeing Kai. Now the two people, with different motives for their search, meet. But can the two of them really find Saya and Kai?
Saya and the others ride on the Trans-Siberian Railroad with Elizabeta. Another Red Shield agent from Russia. While they are riding they are attacked by Chiropterans. Can they defeat them in such a small space?
In an attempt to save Riku, Saya jumps off the train. After being in the blizzard Saya soon passes out. She awakens to find Haji at her side, but she isn't sure if this is a dream or not. Now Saya relives her past with Haji back in a 1920s Russia.
Kai continues to worry about Saya after she jumped off the train. David leaves little space for this as he suggest they press on to find Dr. Ted A. Adams. One of the Delta-67 scientist at the time of the Vietnam war. There search soon leads them to an abandoned nuclear facility. What will they find?
Saya and her group arrives at the hotel where they are supposed to meet up with the others. Not long after arriving Riku comes down with a fever. Saya stays with Riku to take care of him. While Saya is taking care of Riku she is question by Liza about her purpose for fighting the Chiropterans. When Saya cannot answer Liza's questions Liza says something very shocking to Saya.
David and the others return to Red Shield headquarters where they are checked for any signs of Chiropteran infections. Meanwhile Ashmel, Solomon, James, and Nathan meet up to figure out a what to do about Saya. Also Kai finds out something from Joel's diary.
As Okamura and Mao search for Kai and answers to a few of their questions, Saya and Hagi continue their journey only to be stopped by a mysterious black-hooded group who want more than to start a fight. Calling themselves the Schiff, they have but only one person in mind who they believe is the key to their survival . Now Saya and Hagi must deal with this new threat, but, can they?
Saya arrives at "The Zoo", the ruins of Joel's mansion. There she recalls when she first met with Hagi, what happened to make Saya turn Hagi into a Chevalier, and the mansion burning down. What happened there long ago?
Saya and Hagi return to "The Zoo" again and have a run in with Solomon. Hagi makes an attempt to defeat him, but Solomon easily wins. He then reveals to the two that he is a Chevalier and more Chevaliers are trying to kill Saya. But unlike them he is against it. As they are talking David, Kai, and Riku arrive at "The Zoo". What is Solomon after and will Saya and Hagi be able to prepare to fighting the other Chevaliers?
Saya and Diva finally face off after Riku is lured into the bell tower and Diva drinks his blood. With a new will to fight, Saya begins to attack her sister, bust stands no chance as she is tossed clear through a wall. Can Saya really defeat her sister? And what will she do to save Riku?
Okamura and Mao arrive at the Zoo finding a broken sword. Meanwhile Saya and the others rush back to Red Shield HQ carrying a wounded Riku. Can they get there in time to save Riku?
Riku's eyes are now open and he is wondering about his current condition, including his incessant thoughts of Saya and his unquenchable thirst. Kai tries to make him eat to prove to himself that Riku is not a chiropteran or Saya's chevalier, but a human. However, Riku is unable to eat much and can't get to sleep at night. The Schiff attack the ship and Riku is injured by one during the fight. After seeing Riku is now Saya's second Chevalier, they flee as Riku burns with pain from needing blood. Kai allows Riku to feed on him and is thanked sorrowfully by Riku for doing so.
Kai finds out that Riku is now a chevalier. He wanders around Paris wonder what he can do, when he meets Irene on the observation deck of the Eiffel Tower.
While the Red Shield is preparing for another attack by The Schiff, Okamura and Mao suddenly appear.
After the Schiff's attack, Saya agrees to share her blood with Irene. After drinking her blood, Irene's body crystallizes and shatters. The Schiff realize that they have been lied to and that it is Diva's blood they need to survive. They leave, taking most of Irene's pieces with them. Saya and Kai mourn Irene's death.
Saya visits Joel's Room at Red Shield headquarters and learns about her and Diva's beginnings as well as the 1972 tragedy in Vietnam from Joel's diary.
While Saya, Kai, Riku, and Hagi go on an outing and Riku tries to repair Saya and Kai's broken relationship, Diva demands Carl bring her "that boy," while Dr. Collins and Julia meet with Van about their research into chiroptera. Solomon meets with David and warns him that Diva's chevaliers plan to launch an all out attack on the Red Shield Headquarters in three days, and asks him to take Saya to safety. When David asks why, Solomon says it is because he doesn't want Saya to die. Solomon also reveals that the Red Shield has been betrayed from within. David quickly takes Saya and the others back to the ship, leaving Okamura and Mao behind. Solomon and the other chevaliers discover that Carl and Diva have disappeared. Dr. Collins reveals to Julia that he doesn't think chiroptera should be completely destroyed and that he knows about the planned attack on Headquarters. While the Red Shield prepares for the coming attack, Riku convinces Kai to play catch with Saya, which helps them finally return to normal. As they stand on the deck, Saya and Riku hear Diva singing just before Carl and Diva attack the ship. As Carl begins killing the Red Shield operatives, Diva wonders where "that boy" is.
Saya and Hagi search for Diva as Kai and Riku go to join David. Kai hears men screaming and goes to investigate, leaving Riku alone on one of the decks. He can hear Diva calling for him, but Kai returns and they head to the conference room. Saya finds Carl, but leaves Hagi to deal with him and so she can continue looking for Diva. Kai and Riku join some of the operatives at and elevator that will take them to the conference room, but when it arrives Diva is in it. Kai grabs Riku and runs, taking refuge in a storage room, while the men try to stop Diva. Saya finds the men's bodies, but Carl appears again and she's forced to fight him. Joel and David agree to activate the ship's self-destruct sequence to try to entomb Diva in it. Kai and Riku hear the warning about the self-destruct sequence, but Diva finds them. Kai shoots her, but she instantly heals and she knocks him away, leaving him barely conscious while Diva rapes Riku. Saya and Carl's battle takes them to the same room, where Diva is holding Kai and threatening to give him her blood. Saya stabs her, but as she forgot to add her blood to her sword, Diva just laughs and shoves her away. When she falls, Saya spots Riku's naked, cracking body near by; Diva taunts Saya that she gave him her blood, killing him. As Hagi holds off Carl, Kai and Saya watch helplessly as Riku's body shatter completely. David and Lewis find them and lead them back to the ship deck. They had tried to seal Diva and Carl in the ship's hold, but they easily break out and Carl seriously wounds Joel. Saya and Hagi stay to fight them while the others get away to safety. As Kai watches from the departing helicopter, the ship explodes.
One year has passed since Riku's death and the destruction of the Red Shield Headquarters. Kai, Lewis, and David are now in London, living at a shelter for war orphans run by Gray, an ex-military man and David's former instructor. Kai now wears the crystal chunk from Riku's body around his neck in the form of a diamond-shaped pendant. Devastated by the events and with his spirit broken, David lives in a drunken stupor. Joel, confined to a wheelchair from the injury Carl gave him, brings Kai some special bullets they hope will be able to kill chiroptera. He also reveals that Julia is in the United States with Collins. Joel thinks David hates him for what happened and he blames himself for Riku death. Kai tells him he is determined to stop Diva and her chevaliers, and that he must do all that he can until Saya returns. Gray lectures David on his walling in self-pity when Kai has turned his loss into his strength and found his purpose. Later, Kai pours out all of David's alcohol, asking him what he would say to those who died. David says it is pointless without Saya, and Kai yells at him it is his job to wait for her. Meanwhile, in the US, James and Van give a demonstration of their new soldiers, the Corpse Corps. Three of the soldiers kill a single chiropteran, and Dr. Collins tells Julia they don't need Saya anymore. The US agrees to use them. As the Corpse Corps are transported, several Schiff watch from the shadows. That night, Kai and Lewis are out hunting chiroptera, but the new bullets do not work. As they find themselves surrounded by three chiroptera, Saya and Hagi appear.
Saya saves Kai and Lewis from the chiroptera, but collapses afterwards. They take her back to Gray's house to recover. David learns Saya is at the farm, but doesn't react. When Monique touches the sleeping Saya, Saya pops her awake and almost attacks her. She barely acknowledges Kai's presence and calls Hagi to leave. Gray won't let her leave while she's still weak, though, and manages to get her to stay for breakfast. Kai tells her about David, but she cuts him off telling him it isn't relevant to her and that he should go back to Okinawa. Hagi finds David throwing up behind a building and asks if he's given up fighting. While they talk, a chiropteran attacks the farm, having followed Saya's scent. It gets upstairs and goes after Monique. Kai shoots it but is knocked aside. David also shoots at it, but is attacked. Saya, unable to find her sword, attacks it with a kitchen knife coated in her blood and kills it, then leaves with Hagi. As they walk through London, they spot an advertisement for a performance by Diva, who has changed her appearance to look similar to Riku. David and Kai also see the ad on TV.
James uses the Corpse Corps to attack the Schiff. During the battle, it is revealed that they are "improved" clones of Moses. The Schiff, already suffering from Thorn, are being badly beaten. Lulu manages to escape and runs to where Saya and Hagi are resting in a church. Lulu begs her to help them before collapsing from her own wounds. Saya agrees to go, but when they arrive at the warehouse, Dahz is dead, and Gudrif dies shortly afterwards. Only Moses, Karman, and Lulu are left. James reports back to Amshel that he wasn't able to kill all of the Schiff, but Amshel says it is no problem. Amshel puts James in charge of killing Saya despite Carl's objections. That night, the last three Schiff bury their comrades. Lulu asks Saya if she will fight with them to defeat Diva, but Saya says she fights alone, and will not grieve the loss of anymore comrades. Lulu tells her she has lost her hope. She also tells her where Diva will be. As Lulu leaves, she asks Saya to please remember her, because she doesn't want to be forgotten. The three Schiff go to the museum and again fight the Corpse Corp. They are losing when Saya and Hagi arrives. When Saya destroys one of the Corpse Corp, the other two retreat. Moses, Karman, and Lulu pledge to go with Saya, not as help, but because it is the only way they can survive. Meanwhile, David goes to see Joel, sober and no longer drinking. Joel tells him he wants to revive the Red Shield. He later meets with Okamura and Mao and asks them to find out who is sponsoring Diva's upcoming concert.
James and Diva leave to go to a luncheon, but Diva gets him to take her to Royal Covent Garden so she can sing. David meets with Mao and Okamura who tell him that Diva's opera is being jointly sponsored by Cinq Fleches and Goldsmith Holdings, that the two companies have partnered to produce food for the military forces across the countries, and that they have a research facility on the outskirts of London being run by Van. David uses a stolen ID to infiltrate the lab where he discovers Julia and learns a little more about the research being done. He's almost captured by Van who remembered David from Vietnam, but David instead uses Van as a hostage to escape. At the opera house, Saya, Hagi, and Kai battle with James while Nathan watches. Saya's sword is unable to penetrate James' iron-like skin, leaving James an opportunity to kill Saya. However, Nathan stops him and makes him leave, promising Saya he would find her a "suitable" stage to die on. Weakened from the battle, Saya feeds on Hagi. Kai turns away, then looks back to find both have left.
Gray and the others prepare for Javier's birthday party. While shopping with Monique, Kai spots Saya and Monique asks her to come to the party, which Saya agrees to do. Karl steals the Corpse Corps without Amshel's permission to go after Saya and Amshel sends Solomon after him. While Kai and Saya are talking, Karl arrives to battle her. Hagi, the Schiff, and the others deal with the Corpse Corps while Saya battles Karl. Karl grabs Saya from behind and bites into her, planning to drink all of her blood to kill both her and himself. Solomon arrives and cuts off Karl's arm, giving Saya the chance to stab him through her own body killing him. He orders the Corpse Corps back to their beds, and before disappearing, tells Saya that Diva is on her way to Christina Island.
Unable to get a boat on her own, Saya reluctantly agrees to go to Christina Island on the boat the Red Shield and the Schiff accompanied. When they arrive, the three Schiff go off on their own, despite Kai's warning to stick together, and engage numerous Corpse Corps. David, Lewis, Kai, Saya, and Hagi continue towards where they believe Diva, but first must face off against James. While Saya continues to battle James, Kai takes Hagi to save the Schiff. With the help of the Schiff, Saya is able to strike James with her sword. As he falls into a huge tunnel, he manages to pull Saya and Kai in, but Solomon appears and saves them both. He tells them that it was a trap set by Amshel to see if Solomon would tell Saya and that Diva is on her way to New York. Before leaving, he tells Saya he is in love with her and will always be on her side.
Lewis and Okamura confirm Solomon's story that Amshel is a chevalier. Saya agrees to go fishing with Gray, Kai, and the children. David and Joel drop in on a party being held by Amshel and Van Argiano to celebrate the American branch. While there, David talks with Julia, but is interrupted by Dr. Collins. Joel also talks with his "Uncle" Amshel, discussing the new business. Mao and Monique talk about their respective feelings for Kai, and his lack of feelings for them. To Van's shock, Amshel makes him the CEO of the Cinq Fléches' American operations due to Solomon's continuing absence. Saya is sleeping longer and becoming harder to wake up. The next day, the group says their good-byes to Gray, Monique and the children and heads to New York.
In New York, Saya rests in a hotel room and receives more blood transfusions while Hagi takes care of her. With her condition worsening, Saya grows more contemplative. She apologizes to Hagi for making him a chevalier, but Hagi assures her he has never regretted it. Solomon goes to where Diva and the others are, wearing a black suit instead of the white suits he used to prefer. Solomon asks Diva if she remembers the day they met. He tells her that he can not see Saya as his enemy and proclaims his love for her. Diva tells him to do what he likes and strips him of his role as her chevalier. Amshel refuses to let him leave alive, but Nathan stops their fighting and Solomon says he will live with Saya as Solomon Goldsmith.
A month after the last epiosde, the apartment Okamura and Mao in Los Angeles were using is blown up, so they join David and the others at their cheap apartment in Little Italy, New York. Saya is continuing to grow weaker and requiring more sleep. Mao makes her promise to return to Okinawa and go shopping with her after everything is over. Kai and Lewis meet with one of Lewis' old CIA contact, and learns that Goldsmith has deep connections to the US military and the Secretary of Defense. While meeting with a retired general, Joel learns Diva will be performing at an Air Force base in North Carolina. Mao overhears Hagi and Saya talking about Saya's time to go into her 30 year hibernation approaching. Though she's furious, Mao agrees to keep her secret and makes a promise with her that no matter what, Saya will return to Okinawa. Meanwhile, Van puts Dr. Collins in charge in the research division at Cinq Flèches, while Amshel has Julia replace Dr. Collins as Diva's primary care physician. Julia learns that Diva is pregnant and that Amshel is one of Diva's chevaliers.
Saya and her group have infiltrated the air force base. Following Julia, David learns Diva appears to be eight weeks pregnant and that the babies will be born soon. Once Julia and Collins are alone, he attempts to kill her, but David intervenes and is shot. At the same time, David manages to stab Collins in the arm with a scalpel, after which Collins runs away. Meanwhile, Amshel captures Kai and takes him to Diva, who wants to make him a chevalier. Saya is able to get Kai away, but when she goes after Diva, Amshel captures her, and Hagi is caught by Nathan. While they fight, several people attending the concert suddenly change into chiroptera and begin killing the other guests, only to be killed themselves by the Corpse Corps. Solomon appears and saves Saya from Amshel before flying off with her, after which Hagi frees himself from Nathan's grasp and leaves to rescue Saya.
Saya wakes up in Solomon's New York penthouse apartment, while Hagi searches for her. Solomon explains that he has left everything behind for Saya, including Diva. He pledges his eternal loves and asks Saya to be his bride. He pledges to protect her and fulfill her every wish. As they talk, Solomon realizes Saya's time of sleep is coming, and swears he would kill Diva if Saya ordered him to. Hagi appears to retrieve Saya, saying she is his reason for being. Solomon won't let her go, and they begin a battle. As they fight, Saya gets dizzy and falls from the building. To save her, Hagi unleashes his true form for the first time in the series. When they land, Saya gently rejects his feelings, and tells him killing Diva is her job. She and Hagi fly off, returning to the apartment. Meanwhile, Julia goes with David to the hospital. As he is rushed to the emergency room, he asks her to come back to them. Julia keeps vigil over him as he lies unconscious in the hospital, and kisses him. Back at the apartment, Mao kisses Kai and confesses her love, but also accepts that his only thoughts are for Saya.
Julia, Kai, Lewis, and Saya discuss Diva's pregnancy and David's slow recovery. Lulu comes to visit Saya again. Julia tells them what she learned about the Schiff experiment and the Corpse Corp and that they could suppress the Thorn in the Schiff with Diva's blood. Kai takes Moses a shipment of blood, as part of their agreement that the Schiff won't attack humans if the Red Shield supplies them with blood. When Lulu returns home, Karman forbids her from seeing Saya and the others because they are too different from the humans. Moses enter and Karman yells at him too. As they argue, Moses and Lulu discover that Karman has been inflicted with the Thorn. Karman runs out, unknowingly passing James. As the sun rises, Lulu asks Kai and Saya to help her find Karman. Karman goes to a hospital and attacks a nurse, but then sees a vision of Irene and the other Schiff who've died. Realizing they are still alive in his heart, he leaves the woman alone. That night, James goes to see Moses, revealing that much of his body is now that of the Schiff and that he was rescued before Saya's blood could completely destroy him. He offers to help the Schiff try to cure the Thorn, just as Kai had. Moses finds Karman on the roof with his hood down so he can die in the rising sun, but Moses stops him and promises to save him.
Unable to find Karman, Kai and the others return to the apartment. Moses arrives and after apologizing to Kai, tells him he must die. Saya blocks his scythe swing, but Moses manages to knock Kai out of the window. Hagi catches him before he hits the ground. Kai runs, trying to stay in the light so Moses can't attack him. When Moses corners him in an alley, Kai tries to convince Moses to stop and find out why he's doing this, but Moses won't answer. Backed against a fence, the sunlight stops Moses and Kai escapes. He runs to Central Park, but Moses finds him again and begins chasing him around the forest. Meanwhile, James goes to the Schiff's hideout and tells Karman that Moses is going to kill Kai to save him, even though it won't really work. James tells Karman it is for his revenge, because the existence of the Schiff has separated him from the one he loves the most. After seeing his new half-Schiff body, Diva declared that James wasn't her James anymore and hates him. In the park, Kai manages to shoot off Moses hood, but then runs over to cover him back off so the light wouldn't kill him. Spurning Kai's sympathy, Moses strikes at Kai with a spike he grows on his hand, but Karman appears and takes the blow meant for Kai instead. Karman calms Moses down and before they left, asked Kai to give Lulu their weapons. They go to a bridge where Karman tells Moses they won't be forgotten since Kai will remember them and pass on those memories. Together they stand and face the setting sun, their hoods removed. As they are enveloped in green flames, they agree that they are glad they met. In the apartment, Lulu cries over their weapons.
Mao, watching Saya and Hagi talk and hold hands, asks Kai if Saya is her competition for his love. She sends him out shopping, then asks Saya to catch him because she has some embarrassing things on her list, then keeps Hagi from following by saying she needs his help around the house. At the subway station, Saya starts to faint, almost falling in front of the train but Kai catches her. Later, Saya promises Kai that she will always protect him and asks him to take better care of himself. Kai has a key of their father's bar made for Saya, so they can run it together. David leaves the hospital and returns to work. Saya and Hagi remember her making him promise to kill her, with his own hands, when everything is over. As he, Lewis, Julia, Joel, and Okamura discuss the situation, they realize the American government has Cinq Flèches deliberately creating chiroptera in America, and abroad, to create enemies they can then rescue the people from using the Corpse Corp. Julia explains to them that Diva's singing, when heard in person or a live process, it increases the effectiveness of the D-base that causes people to turn to chiroptera from 3% to 100%. Meanwhile, Nathan visits Solomon and takes him to see Diva and the babies, which Amshel "cut out of her stomach." Nathan tells him that now that the babies are born, he has no reason to fight his family anymore. To prove his commitment to Saya, Solomon attempts to kill Diva, but Diva easily defeats him and leaves him badly wounded. As Diva takes the babies inside, Nathan wonders if even a chevalier can survive such wounds.
In order to keep Diva's public performance from being broadcast, David, Lewis, Kai, and Okamura go to Staten Island to blow up the satellite dishes. Though she is growing weaker and more tired, Saya is determined to fight so she doesn't wake up in a world full of chiroptera. Hagi asks Saya to reconsider their promise, but she makes him ask her to fight again. Amshel orders Nathan to kill Solomon, but Nathan releases him from the dungeon instead. James, in his full chiropteran form, goes to the apartment and attacks Saya. When Saya attacks him, though, her sword bounces off his skin. Hagi and Lulu try to help her in the fight, but the three are losing badly. As James moves to kill Saya with her own sword, Solomon arrives and, in his human form, blocks James' attack. Solomon then swears that he is Saya's chevalier by his own choice and states that it is "beyond blood". He is able to make James drop Saya's sword, but as it falls, it slices Solomon near his chest. James is suddenly inflicted with the Thorn, and Saya is able to strike the killing blow to his head. Solomon tells her to call his name if she ever needs him, then leaves. Though Hagi sees the cut from the sword, Saya does not appear to. Amshel finds Solomon in an alley trying to hold on, but he crystallizes in Amshel's arms from Saya's blood on her sword. Nathan and Amshel are now Diva's only surviving chevaliers.
Saya, Hagi, and the Red Shield goes to the Metropolitan Opera House to try to stop Diva's performance. Before the show starts, Nathan tells Amshel that the world exists to showcase Diva's beauty, as was predestined before she was born. When Amshel says Nathan talks like he was there, Nathan says he was and that before Diva was born, there was their "mommy" and her faithful chevalier. Kai confronts Hagi and demands to know what else they are hiding besides the coming hibernation time and begs him to take care of her. While they talk, Saya slips the key Kai gave her into his coat pocket and whispers goodbye. Saya and Hagi go to try to kill Diva before she can take the stage, but before she can charge Diva, Saya grows woozy again and can't attack. Hagi attacks Diva, but she easily dodges him. Hagi and Saya fight against Amshel. After he knocks Hagi out, Amshel tells Saya that if she had never set Diva free, Diva could have been his and his alone. He admits he has a constant obsession with Diva, which he views as the ultimate form of love for her. Diva begins singing, and people in the audience begin changing into chiroptera. Lewis is able to blow up the relay stations, but it doesn't work because they relay the signal through the military satellite feeds. Kai, David, Lewis, and Lulu go to the relay vans and destroy all of the equipment to finally bring down the world-wide broadcast. They get surrounded by chiroptera and David is injured. Hagi attacks Amshel so Saya can go after Diva as Nathan watches from the audience with the babies beside him.
Grant, the Secretary of Defense, escapes, and leaves Van behind to face the chiropterans alone. Saya tries to explain to Diva why she wants to kill her to protect the humans, but Diva reminds her that she was the only one who was ever treated as a human being. Diva returns to her regular form while she and Saya argue over the existence of chiropterans. Backstage, Amshel tries to upset Hagi by reminding him that his parents sold him to Amshel for a loaf of bread, but Hagi tells him he is grateful because it enabled him to meet Saya. Amshel and Hagi assume their true forms and begin fighting, going through the roof outside where Hagi is badly losing. Meanwhile, Lewis runs out of the transmitter trailer as a decoy to draw the chiropterans away with Lulu's help while Kai gets David to safety. Hagi gets the upper hand on Amshel and impales him on the top of a skyscraper, but loses a wing in the battle. As Amshel tries to pull himself off, lightning strikes the rod, appearing to kill him by electrocution. Diva asks Saya is she is going to kill her babies as well, since she believes chiropterans shouldn't exist. Both load their swords with blood and begin their battle. Nathan, holding the babies, and Hagi watch from the audience, having agreed that in the end it is the queens' fight. Saya and Diva each impale the other with their blood-soaked swords, but Saya heals while Diva begins crystallizing. Saya cries and tries to help her, but Diva begins shattering. Nathan brings the babies to Diva, and she tells them good-bye and imagines herself holding them before she dies. Nathan says all she wanted was a family, something Amshel never understood, and explains that when she became pregnant, Diva's blood lost its potency. Nathan asks Saya to kill him, as he no longer has a purpose with Diva dead, and Saya does. Hagi comes up behind her and wraps his arms around her as she cries. Kai comes in and Saya tells him that she must die after she kills the babies.
With the song stopped and Diva dead, the chiropterans begin howling and the Corpse Corps stops fighting. Inside the opera house, Saya explains to Kai that she fears that if she and the babies live, they would be used as weapons of war. Kai promises to make anyone who won't accept them understand and to always protect and love them all. Hagi tells Saya that he has loved her from the moment they met and that for once, he is going to disobey her. Taking her sword, he begs her to live on and kisses her forehead. Saya cries and says she wants to live before kissing him. David bursts in and tells him to hurry and leave because Option D has been activated. Kai and Saya carry the babies as the group leaves, but Amshel, who survived his fight with Hagi, attacks the group, ripping off Hagi's arm with his breath attack. Saya swears to protect the babies, but when she tries to attack Amshel, Hagi grabs the sword from her and pushes her away before stabbing Amshel himself. As Amshel begins crystallizing, he stabs Hagi through the chest with his hand and the roof collapses on them both. Saya screams his name and the military planes begin bombing the opera house. A month later, Saya and the others are back in Okinawa. The number of chiropteran attacks continues to decrease and Julia, who is now pregnant with David's baby, has found a way to prolong Lulu's life. Nathan, who survived Saya's attempt to kill him, is seen at a press conference in America about the criminal investigations surrounding Van and Cinque Fleches' close involvement with the U.S. military. Saya and Kai are hosting a party at the reopened restaurant, inviting their friends from the Red Shield and their schoolmates. Okamura and Mao plan to go to the Middle East together. During the party, Saya slips outside and looks back at the restaurant with tears in her eyes before she collapses. Kai catches her and agrees to wait to tell the others. He carries her back to the Miyagusuku family crypt where she woke up. She whispers thank you as she drifts off to sleep. As he carries her up the steps toward the crypt, he promises to make them all happy and care for the babies until she wakes up. After the final credits, Kai is shown with Diva's children going to visit Saya, still asleep in the crypt. When they arrive, he sees a pink rose with a blue ribbon left behind by Hagi, and tells the children to leave it alone.