A gate to another dimension has burst open, and from it emerge gigantic invincible creatures that threaten all of humanity. Earth's only defense is a mysterious group of warriors who have co-opted the alien technology in order to fight back!
Approximately four years ago, a gate to another world opened in Mikado City, and invaders called Neighbors appeared.
Border sees the Neighbor Yuma as an enemy… but Osamu is unable to view him as someone with hostile intentions, and trust begins to bloom between the two boys. Osamu finds himself caught between his own thoughts and the rules of the organization he belongs to, Border.
Combat-use Trion Soldiers attack when a gate opens in Osamu’s school just outside of the Forbidden Zone. Worried he’s not strong enough, Yuma tries to stop Osamu from fighting back, but Osamu’s determination to save the other students is limitless.
Osamu gets more trouble than credit when he claims to have defeated Trion Soldier Marmod. Really, he’s covering for the Neighbor, Yuma. Kitora, an A-rank Border Agent, is furious with Osamu for stepping out of line… But does she suspect the truth?
Kitora boldly jumps onto the back of Ilgar, a new type of Trion Soldier, while it’s mid-flight and bent on attacking the city below. Suddenly, Ilgar transforms, enters self-destruct mode and plummets toward its target. How will she escape now?!
Yuichi and Osamu's critical mission to investigate the abnormal gate puts a lot of pressure on Osamu. Meanwhile, Yuma follows Replica’s advice and conducts an investigation of his own. The next morning, Osamu and Yuichi have a fateful meeting with Yuma...
Osamu reaches out to Yuma and Replica. He and Chika learn some critical information about Neighbors from Yuma, but they're soon discovered by two A-Rank agents, Shuji and Yosuke; they're searching for a Neighbor in human form...
Shuji and Yosuke are soon joined by two snipers and they wage a four on one battle against Yuma. Osamu seeks help from Yuichi for the human-form Neighbor but is told to stand down.
With Shuji's squad singlehandedly defeated, the Border Agency's executives order Yuichi to defeat Yuma and recover the Black Trigger. Osamu worries about Yuichi's impending clash, while a secret hidden by Yuma is slowly exposed.
Yuma is invited to join the Border Agency’s Tamakoma Branch, and agrees on the condition that Osamu and Chika join with him.
Yuma's revealed why he came from the other world. Chika's resolved to join the Border Agency so she can go to the other world in search of her friend and her older brother.
Osamu, Yuma and Chika set their sights on joining the expeditionary force. First, they'll need to win a tournament called the Rank Wars.
Yuichi and Yuma join forces...while Commander Masamune begins to fear the power gathering in the Tamakoma Branch.
The battle between the A-Rank attack unit and Yuichi Jin begins to rage. In the face of top-level agents, Yuichi tries to turn it into a test of endurance. But just as Shiro Kikuchihara gets by him, Yuichi's Black Trigger goes off!
Yuichi finally reveals his "Wind Blade" technique with the Black Trigger. As his battle with A-Rank vets Kei and Soya reaches its climax, the Arashiyama Unit shows up in support and clashes with the Miwa Unit. Who will emerge victorious?!
Yuichi Jin and the Arashiyama Unit repel the enemy. Receiving news of their elite squad's defeat, the Border Agency's headquarters starts to get nervous.
The day of Yuma and Chika's initiation into the Border Agency arrives. Osamu nervously stands by in support, while they draw the scrutiny of their new peers. At that time,
Osamu readies for his practice fight against Soya Kazama. Soya is a symbol of overwhelming strength, while Osamu has yet to land a hit in over twenty battles!
Osamu doesn't know how to deal with his new reputation as "the guy who tied with Soya Kazama". He is soon challenged by one of his fellow agents to a Rank War.
Yuma and Shun Midorikawa's fight begins. Yuma quietly rages over Shun's humiliating public defeat of Osamu. How will he fight against the A-rank vet? Meanwhile, Commander Kido convenes a meeting to prepare for the forecast massive Neighbor invasion.
The Border brass puts together a strategy based on Replica's information about Neighborhood. Meanwhile, Yuichi Jin senses impending danger for Osamu and asks Shuji Miwa for help. A massive battle with the Neighbors is about to begin in Mikado City!
The Neighbors' large-scale invasion finally begins. The invading army of Trion soldierrs is countered with a defense strategy. Just as the battle seems to turn in Border's favor, a new Trion soldier, Rabbit, emerges from a defeated Bamster!
Border seeks a way to counter the new Trion soldier, Rabbit. Yuma prevents Trion soldiers from infiltrating the city, but is mistaken for the enemy and attacked by the B-rank Chano Unit. Meanwhile, an Ilgar Trion Soldier menaces Border headquarters!
Trion soldiers from Aftokrator appear all over Mikado City. Border is forced to divide its forces to deal with their numbers. Chika's C-rank unit is attacked while organizing the civilian evacuation. What is Aftokrator's true goal?
The C-rank units are revealed to be the true target. The battle intensifies as Hyrein sends humanoid Neighbors Enedora and Ranbanein into combat. Osamu fights to give the C-ranks a chance to escape, but Rabbit's merciless attack on Chika continues!
Aftokrator's humanoid Neighbors are unveiled. These so-called Horn Triggers overwhelm the Border agents with powerful Triggers! The A-rank Kazama Unit uses Kikuchihara's Side Effect in a skillful combo play against Enedora, but will their luck continue?
Kizaki, Karauma and Konami fight the sinister Hyuse and Viza so that Osamu and Chika can escape. Meanwhile, Ranbanein easily defeats Chano unit and takes on Yoneya, Izumi, Midorikawa and Azuma's combined forces. Can Jin's worst case scenario be prevented?
Kizaki has figured out Hyuse's Trigger, Lambiris. He orders Karasuma and Konami to protect the city while he holds off Hyuse and Viza.
Viza and Hyuse continue to pursue Chika, but Yuma and Jin arrive just in time. Yuma faces off against Viza while Jin battles Hyuse. Osamu and Karasuma lead Chika and the C-rank agents to Border HQ. However, Enedora's rampage has the HQ in chaos!
Suwa unit traps Enedora in a virtual training room. Director Shinoda goes to offer them back-up, and the tides begin to turn for Border. Mira's 7 Rabits block the evacuees led by Osamu, as the Aftokrator leader Hyrein heads out to capture Chika!
Hyrein's attack turns Chika into a cube. Osamu blames himself, but is inspired by his fellow Border agents to race for Border HQ in an attempt to save Chika
Director Shinoda corners Enedora in the virtual training room. However, Enedora's powerful Black Trigger attack are more than a match for the Border agents' group attacks. Meanwhile, Karasuma faces Hyrein and activates his true power, Geist!
Karasuma uses Geist to buy Osamu enough time to make it to the base with Chika's cube. While Geist is immensely powerful, it forces a Bail Out within 200 seconds. Can Karasuma change the future predicted by Jin?
Skillfully using Red Bullet, a Trigger for advanced users, Miwa proves himself the equal of Hyrein. Facing defeat at the hands of Viza's Organon, Yuma recalls what his father taught him. Taking Osamu's words to heart, he commits to a risky plan!
Yuma defeats Viza but is low on Trion. Miwa is separated from victory. Osamu is captured by Hyrein within sight of Border HQ. Miwa activates Fujin and fires on Hyrein with Yuma. With 7 seconds to go until the foretold future, can Yuma and Osamu win?
Aftokrator retreats, but the wounds of the war are deep. Border struggles to revitalize Mikado City, Yuma searches for the missing Replica, and Osamu remains unconscious. In his dreams, he recalls why he joined Border, and why he seeks to protect Chika.
Osamu wakes up in the hospital, where his mother and Shiori tell him what happened during his week-long coma. Suddenly, Business Director Karasawa takes Osamu out of the hospital to a press conference about the battle. What are Karasawa's true intentions?
PR Director Netsuki sets up Osamu as a scapegoat for the devastation from the battle. But Osamu speaks from the heart and changes everyone's mind. Next, Osamu, Yuma and Chika must prepare for the next step towards A Rank: the B Rank Competition!
Mikumo Squad's B Rank Competition debut ends in a stunning win. Their next opponents are the 8th ranked Suwa Squad and the 10th ranked all-Sniper Arafune Squad. Osamu tries to come up with a Tamakoma-support strategy, but can he lead his team to victory?
The squad puts into action their plan to defeat the more experiences units. Their trump card will be...
Yuma joins Round 2, armed with a new Option Trigger. Meanwhile, Arafune Squad finds itself hounded by Mikumo Squad and Suwa Squad. Arafune goes back to his roots as a former Attacker and uses the Attacker Trigger Kogetsu. What will Osamu and Chika do?
Mikumo Squad wins Round 2 and is promoted to 8th rank. Their next opponents are the 13th-ranked Nasu Squad and 9th-ranked Kuruma Squad. Yuma requests Individual Rank Competition with Kuruma's ace Attacker, Ko Murakami. What is Murakami's secret ability?
Shocked to learn that Yuma lost in a solo rank battle, Shiori explains Murakami’s Side Effect. The other units prepare for Nasu Squads stage selection.
Round 3 begins in a violent storm. While Mikumo Squad and Kuruma Squad focus on finding each other, Nasu Squad carries out their strategy as planned. Just as Nasu Squad seems to have the advantage, Chika's Ibis strikes. Can Mikumo Squad grasp victory?
The team members are divided due to Chika dropping the bridge. While Osamu goes after points on the east side, Yuma faces off against Murakami and Kumatani in a triple-attacker showdown in the west. The stakes are high for all teams. Who will win?
Kuruma Squad's Murakami and Mikumo Squad's Kuga clash on the West Bank!
The B-Rank Competition's third round finale! Yuma triumphs while the team leaders fight on the east side. Osamu seeks to change the tide of battle by drawing water into the city and pitting Nasu against Kuruma. The three-way battle is about to conclude.
Mikumo Squad joins the B-rank upper tier. The fight against the top B-rank squads will be a touchstone for promotion to A-rank. Anticipating this, Osamu struggles with his inability to score a single point on his own and comes to a conclusion.