Originally Posted by
Ryllharu
I think you're misunderstanding how he was torturing her.
Misaki is, or was, a good person (at least Akiho still thinks so). Kimijima was constantly mentally torturing her about being a murderer. He always making her feel guilty about the method used to save them, when there very likely had been a less violent way she could have stopped it. Then, it was when he started manifesting in front of other people and threatening to "haunt" Akiho and Kai while she continued to resist. That last part is what finally broke Misaki and made her submit. Over the next ten years, he continued to harass and torture her mentally. That's a huge amount of time to mentally condition a person. At some point, she basically got brainwashed, and believes in his cause.