This manga sure has a lot of crazy twists. I knew about the sensei being nuts, and it's part of the reason I picked it up, wow, my expectations were exceeded
I disagree she's a victim of Reiji, she's an adult and could make her own decisions. And her first decision was to sleep with a student who was simply asking for help and to pretty much confine him in her flat. There was something wrong with her from the start. That said, she's such an enjoyable character because of how batshit crazy she is, and because she isn't actually evil.
Speaking of evil, I never saw the twist with Reiji's mom coming. I starting off thinking she was guilt tripping him, but then when she revealed her weakness to Reiji and Gen showed her what she had been doing for him, I felt super bad for her and saw her as the biggest victim in this. Imagine how low my jaw dropped when it was revealed she's an evil manipulative bitch. She's made so many people suffer to get what she wanted. And I'm sure it's not over.
Chako was my favorite for a long while and was definitely the most normal character of the cast. She experienced regular teenage angst, that's it. Too bad that in her case, Reiji definitely did en up fucking up her life. She used to be so happy and energetic... that said, she's looking damn fine for someone with anorexia. She said she's still no match for Nagi but I'd say she's pretty close.
Nagi... not much to say about her because the story hasn't revealed anything yet. She's just a husk. I was happy her meeting with Reiji was no coincidence and it was all part of Nozoe's plan, it made more sense than an idol retiring to the boonies and wanting to kill herself with the first boy she meets (after having sex with him of course). If I had to choose, I'd say I like her though. Great looks and I'm interested in her. I was also really relieved Gen didn't have her gang-raped like I was expecting.
Gen... I just feel sorry for him. He's as much a victim of Yuko as Reiji is, if not more.