You know what? I'll put hypothetical money on Kitami protecting Tojo by getting stabbed himself. Although him dying could be up in the air, seeing how two people who suffered catastrophic falls somehow survived.
Kitami fully dying would make sense at that point from a 'closure' standpoint. He feels like he got left behind by Himari, and that his life has been devoid of meaning because he's trapped in the past with the trauma off the abuse. He's effectively destroyed his life through seeking vengeance anyway, but he also risks taking
Himari down, because he did it all "in her image". And however twisted Kitami might be at this point, he genuinely cares about Himari.
So giving his life to save her, maybe making it so those USB drives are released so that her name is also cleared of everything he did in her stead, would sorta give his life meaning, in a way. He can finally actually protect her, and "give penance" for his crimes up to this point. Him not dying is also a thing that could happen, but he killed one kid, is partially responsible for pushing another kid toward ruining his own life, and permanently crippled one person and likely seriously injured another. So it's possible his life would be over anyway once those drives are discovered by authorities, so dying might be "his way out", at that point, and at least allows him to do something to help Himari in the end.