All of them need therapy, especially the ML. But woooooooo it was one hell of a trip. The yandere/stalker ML had been obsessed with the co worker for over 2 years, learning everything about her.. Even reshaping his body to her liking. Eventually, he rubbed off on her bc she in turn became perverted herself. Loving his crying face and trying to "train" him. Her inner S definitely was awakened. I also liked the additional secret perv, met at the Goukon, Kurai who definitely flip flopped from the FL to the ML cuz he's an extreme masochist and the ML, he thought, was a more extreme S. (I think he is too, he just curbs his thoughts bc most are illegal lmao though I don't think Kurai would mind)
Tonari no Seki no Hen na Senpai