Sumiharu Inukai/Relationships

Masataka Ninomiya
Ninomiya and Inukai are close friends and teammates.

Shinnosuke Tsuji
Inukai and Tsuji are close enough to hang out together with their teammates outside of Border, including for the former's birthday. While both are normally serious and task-oriented in battle, Tsuji may reprimand Inukai if he begins goofing around. Even during combat, the Gunner will often take the time to thank and compliment his teammate for his assists. Similarly, Tsuji appears to hild Inukai's aim in high esteem, standing unperturbed among his training targets as the Gunner practices. Inukai addresses Tsuji by his surname followed by the diminutive suffix -chan, while the Attacker appends to his older teammate's surname the more respectful honorific -senpai.

Aki Hiyami
Hiyami and Inukai are close enough to hang out together with their teammates outside of Border, including for his birthday. She addresses him by his surname followed by the honorific -sempai, while he uses her nickname.

Masato Kageura
Inukai is aware of Kageura's contempt for him, but is not bothered by it; in fact, he'll even humor him for it. As such, he has made the effort to say exactly what is on his mind for the sake of Kageura's side effect, later admitting: "This is honestly the best our relationship's ever been."

Yuzuru Ema
Inukai refers to Ema by his first name and the honorific -kun.

Futaba Kuroe
He is very playful with Kuroe, fiddling with her twin tails when they were idling about.

Rokurō Wakamura
Inukai agreed to tutor Wakamura in Gunner techniques for an unknown amount of time. Wakamura refers to him by his surname followed by the honorific -senpai, denoting respect.