|“||Impressive, Mikumo. Dining with three girls like it's nothing...||”|
Tsuji is a tall, light-skinned young man of lean build with dark, narrowed eyes, a straight nose and smooth, short-to-medium jet-black hair. His battle uniform is a suit, similar to a school uniform. Outside of Border he has been seen wearing a light-colored jacket with a high collar over a cardigan and a black undershirt, as well as light-colored shirts and trousers.
Tsuji's uniform consists of a full-body black suit with a vest, tie, and shoes of the same color, and a white shirt. Around his waist is a holster to hold the scabbard of his Kogetsu.
Tsuji is quiet and collected. However, his composure easily gives way to embarrassment when a girl speaks to him, to the point that he is not only unable to have a conversation with her, but even to look her in the eye. The only exceptions are Hiyami and Hatohara. This extreme timidity causes him to be very guarded at school. In combat, he is very task-oriented and does not speak out of turn. He owns up to his mistakes without hesitation and he did not refrain from praising Hyuse's superior swordsmanship after the recruit bested him in combat.
Hiyami is one of the only two girls Tsuji can converse comfortably with, although her guarded personality put him off at first. Since then, the two have grown close, with Hiyami being protective of him when their female schoolmates tease him. The two hang out together and with the other members of Ninomiya Unit on occasion, including a teammate's birthday. Hiyami addresses him by his surname followed by the honorific -kun, whereas he addresses her by her nickname.
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.
Hatohara is one of the only two women with whom Tsuji is able to converse comfortably. Her kind personality put him at ease as soon as they met. They used to hang out together with their teammates outside of Border, including for a unit member's birthday. Tsuji does not appear to resent her for her defection, stating that venturing into the Neighborhood illegally was the only option she was left with. He refers to her by her surname followed by the honorific senpai.
Ninomiya and Tsuji are close enough to hang out together with their teammates outside of Border, including for a unit member's birthday. They do so often enough for Ninomiya to order a drink on his behalf. Tsuji profoundly respects his captain, standing at attention next to his mattress after he bailed out in round eight. Ninomiya addresses Tsuji by his surname without appending an honorific.
Ikoma holds Tsuji's combat prowess in high esteem. Since the latter does not appear to be bothered by Ikoma referring to him by his surname followed by the diminutive suffix -chan, the two are presumably on good terms.
Sasamori and Tsuji appear to be on good terms with each other, with the latter addressing the former by his first name followed by the honorific -kun. The two are close enough for Tsuji to notice a change in Sasamori's personality.
Koarai is presumably somewhat close with Tsuji, taunting him when they clashed in round four. For his part, Tsuji appears not to mind Koarai's informality. Nonetheless, Koarai acknowledges Tsuji's superior swordsmanship and addresses him respectfully, using his surname and the honorific -senpai.
Kirie Konami and Shiori Usami
Tsuji is schoolmates with Konami and Usami, who enjoy teasing him. They both address him by his surname, with the former adding the suffix -chan and the latter the honorific -kun.
Tsuji is amazed by Osamu's ability to hang out with three girls without other male friends present. Upon hearing about his mother, he surmised it to be due to her intensity. Tsuji addresses Osamu by his surname followed by the honorific -kun, whereas the Shooter appends -senpai to the Attacker's surname.
- (To Sumiharu Inukai) "If you keep messing around, you'll get shot."
- (To Yūma Kuga) "Indeed. But too bad... Your opponent isn't me."
- (To Osamu Mikumo) "Impressive, Mikumo. Dining with three girls like it's nothing..."
- Tsuji likes dinosaurs, cream puffs, and butter dorayaki.
- The author quipped that if Tsuji were to fight against Kako Unit or Nasu Unit, he would get crushed due to his timidity around girls.