Michizō Tachihara/Relationships

Ryūrō Hirotsu
Hirotsu is Tachihara's superior in the Black Lizard unit, however, despite this order and hierarchy, Tachihara has casually referred to him as "Gramps" and has poked fun at his rigid nature, stating he was "too uptight" for petty things such as being only 2 minutes late to a meeting. Throughout time, Hirotsu has often acted as a disciplinary guide to Tachihara including stopping fights between him and his fellow battalion leader Gin, telling him not to shoot in a critical situation, and scolding him and reminding him of the ways of the Mafia vs his mentality of a former gang member. Despite these things, Tachihara has always had a respectful relationship with Hirotsu and has been on good terms with him, showing guilt and remorse for cutting him and Gin down and hurting him as he visited them both at the hospital and asking his opinion of if he was really suited for the Mafia. For all his rigid and strict nature, Hirotsu has shown a kind and protective side towards Tachihara by expressing relief that he had "survived" the attack from the Hunting Dog and his pride in him for his qualities of being a "shining example" of a Mafioso.

Gin Akutagawa
Gin is Tachihara's fellow battalion leader in the Black Lizard unit. In the beginning, they had a hostile relationship marked by having intense yet short spats that were typically initiated by Tachihara antagonizing and picking on her by calling her a "creepy man", which would spark her temper. Hirotsu would often have to break up these fights by threatening them with his Ability. Despite this, Tachihara has shown high respect for Gin's assassination abilities as he described them to Higuchi when she demonstrated them via her "rehearsal".

Over time, their relationship became less hostile as Gin became slightly more expressive with her odd attempts of engagement with him (i.e. writing "Congrats" on the ground with her sword when she spotted him with a baby) and asking for advice on certain topics such as "how to refresh someone's spirits" to which Tachihara joyfully suggested going to a batting cage. By the events of the Decay of Angels, Tachihara has developed a better relationship with Gin in that she was now fully comfortable with communicating with him verbally and worried for his wellbeing while he carried guilt and remorse for cutting her down and hurting her along with Hirotsu as he visited them both in the hospital. Despite their history of engaging in petty fights, Gin has shown to have high respect and trust for Tachihara as she showed through her gestures (i.e. laughing at his doubts of being suited for the Mafia) that she does indeed accept him as one of her own.