Kotarō Tomoe/Plot

Background
Three months after Border moved to its publicly known HQ, Tomoe saw Kuniharu Kakizaki on television and thought he was cool. He enlisted about two years later, which caused him to become the first elementary schooler to join Border. He jumped at the chance when she discovered that Kakizaki was creating his own unit and applied immediately.

Large-Scale Invasion Arc
Along with the rest of his unit, Tomoe joins the fight against Lamvanein. The Neighbor forces them into hiding until Kōhei Izumi, Shun Midorikawa and Yōsuke Yoneya join the fight. At Azuma's command, the members of Kakizaki Unit start firing at Lamvanein to pressure him into revealing openings. When the Neigbor targets Tatsuya Kuruma and anticipates Yoneya's ambush, Tomoe, along with Kuruma, Midorikawa and Tsuneyuki Okudera casts his Shields in front of the Attacker, allowing him to close the gap and defeating Lamvanein. Kakizaki Unit is subsequently deployed to defend the southern area of the city. To the best of Tokieda's knowledge, it was the only B-Rank unit to survive Aftokrator's invasion without a single bail out. It was also the recipient of an Excellent Distinguished Service award.

B-Rank Rank Battles Arc
His unit goes up against Tamakoma Second and Katori Unit in Round 5. When they enter the zone, he regroups with his team before approaching the two enemies. When Kakizaki Unit does confront the enemies, Kakizaki and Fumika begin shooting to pressure Katori Unit, while Kotarō flanks them. However, Kakizaki Unit is forced to retreat when they are lured into a position between the opposing teams. After Chika Amatori begins to destroy the buildings, the teams decide to head for Chika. Kakizaki Unit is stopped by Yūma. Kotarō attacks Yūma directly and is launched by Grasshopper up into the air, where Chika hits his arm with Lead Bullet. Pinned to the ground, Kotarō becomes the first to Bail Out after Yūma beheads him.