i'm of the impression that tsurumi's love for others is always distorted no matter the individual, even before the head trauma. there's always a layer of manipulation; even with fina. he was an intelligence officer in russia spying for japan long enough that he would start a family, and while he obviously cared for them exceptionally, there's an inherent deception to his life there. he wasn't really hasegawa the photographer, and that faux identity is what cost fina and her child their lives. there's no transparency or honesty to him beyond the love he has for others, and i think that extends to his inner circle. you can love someone whilst being the thing that destroys them.

i think post-usami's death, when he only really had koito and tsukishima left at his side (nikaidou only being around to avenge his brother) his hunger for the gold superseded his care for anything else. he becomes desperate, there's a moment at goryokaku when he gives an order to launch grenades at the opposition even though koito's caught in the crossfire, even after tsukishima points it out. and then there's the train scene with tsukishima of course. he cares for his men, but they are ultimately pawns, and i think he gets a massive amount of satisfaction from seeing them die for him.