Masataka Ninomiya is a tall and slim young man with brown eyes and neck-length brown hair, typically seen in a black three-piece suit with the jacket left unbuttoned. He holds the distinction of being Border's number one Shooter and the number two overall combatant, serving as the captain of the B-rank number one squad, Ninomiya Squad, which was formerly the A-rank number four squad. Ninomiya joined Border approximately three years before Chika Amatori and Yuma Kuga, initially placed into Azuma Squad alongside Kako and Miwa. After leaving that team, he formed his own squad and rose to A-rank, even passing the selection for the Away Team. However, a teammate named Mirai Hatohara was unable to shoot other people, leading to the entire squad being removed from the Away Team mission. When Hatohara later defected into the Neighborhood with accomplices, Ninomiya Squad was demoted to B-rank as punishment and could not advance for several rank war seasons. Ninomiya is extremely blunt and harsh in his speech, holding ability in the highest regard and believing that praise should only be given to those who are superior to the one offering the compliment. He is highly perceptive in combat and carries a strong competitive streak, once begging his rival Izumi to teach him new techniques even though he was already the top Shooter. His motivations are closely tied to his squad's strength and to uncovering what happened to Hatohara; he later approaches Tamakoma Second to ask for information about Rinji Amatori and shares the story of Hatohara's departure. In combat, Ninomiya relies on his enormous trion reserves, which allow his attacks to deal heavy damage. He is proficient with a variety of shooting triggers, including Asteroid, which he can shape into pyramids, and composite bullets such as Gimlet for armor penetration, Hornet for guided shots, and Salamander for wide destruction. His typical battle strategy involves using guided missiles to force opponents into predictable evasive movements, then finishing them off either by his own hand or with his teammates. During rank wars, he has demonstrated the ability to easily defeat skilled opponents like Yuma and Kitazoe, and he entered a deadlock with Kageura and Azuma that ended in a time-out with his squad victorious. During the Galopoula invasion, he assumed a leadership role and directed the defense of Border headquarters. Ninomiya's key relationships include his squad members Sumiharu Inukai and Shinnosuke Tsuji, his former teammate Hatohara, and his rival Izumi. He also interacts extensively with other captains such as Kageura and Azuma during rank wars. His development is marked by the setback of his squad's demotion, yet he continues to lead them as the top B-rank unit, maintaining his reputation as a fearsome and highly tactical fighter.