tsukumo ima (not really in-depth) analysis
[warning: spoilers for ima's free time & bonding events]
ima genuinely and deeply cares for his sister to the point that he is willing to go to any lengths to protect her. she is the only family he has left and everything he does is rooted in a desperate desire to keep her safe.
(do note that ive only finished 6/100 endings and completed ima's bonding events. my opinion may or may not change as i progress with the game. regardless, i just want to share my current thoughts about him since ive grown to like him as a character)
in order to provide for the both of them, he has taken on countless jobs that are borderline or straight up illegal. it was heavily implied that he was subjected to abuse. and in his desperate attempt for survival, even resorted to using his own body as a means to make ends meet. (he's confirmed 15 years old based from their jp introduction but was omitted from the english localization for some reason)
for him, these sacrifices were worth it because all he has ever wanted is to give his sister a better life.
however, his protectiveness, though well-intentioned, has become too toxic. his need to shield her from every potential harm has led him to take control over her decisions, relationships, and even her sense of independence. by constantly making choices for her and micromanaging her life, he is not only stifling her growth but also denying her the opportunity to develop on her own. his actions, though rooted in love, are robbing her of agency which could ultimately be more damaging to her than the things he's trying to protect her from.
now that kako is growing up and pushing back against his control, ima is forced to come to a terrifying realization that she may no longer need him the way she once did. and that possibility scares him. his entire identity has been built around being her protector, the one person she could always rely on. without that role, he is unsure of who he is or what purpose he serves. he has unknowingly become codependent on her by relying on her need for him to define his own sense of self.
in truth, ima's fear is not just about losing his sister to the world. it's also about losing the only role that has ever given his life meaning. that said, i wouldn’t go as far as to say that his actions and his resistance to allowing his sister to make decisions for herself are completely justified. while his intentions may come from love, the impact is still harmful. it's important to recognize that his behavior, however complex, still crossed a line.
but even though his choices are flawed and pftentimes toxic, i can understand where he’s coming from. he’s someone shaped by trauma, by loss, and by a life spent in survival mode. letting her sister go feels dangerous to him because, for so long, control was the only way he knew how to keep her safe. he is not acting out of malice, but out of fear (maybe even desperation). that doesn't make his actions right, but it makes them human.