Hitomi Kashiwa

Summary
Hitomi Kashiwa was Satou's senpai. She coaxed him into joining the literary club and all they did was play cards and talked about conspiracies. After Hitomi got out of highschool, she became a civil servant. She uses a variety of anti-depressive pills to help with her paranoia.

Personality
She's a very paranoid person, with suicidal tendences, and used to be abused by her boyfriend, she becomes very depressed as well. During the anime, it's showed that she had a close relation with Satou, almost as boyfriend and girlfriend, but both at the time denied a relation, what made both regret after some years.