It's hot but the story makes no sense. The girl was supposed to graduate but the other girl who was sleeping with the teacher gets him to prevent her from graduating. But there weren't any real issues to prevent her graduation and that's not something a single teacher could even decide in the first place...
Then they bullying girls make some incredibly vague half-assed threat towards the victim's friend to convince her to rejoin the tennis club she used to be captain of and then continue to go along with all the blatant bullying they do. Exactly how they have so much power really isn't explained. I mean it when I say the threat is vague and half-assed, Like even if they seized control of the tennis club the friend could just leave it and what could they do to her...
Yes I am over-analyzing hentai. I like the basic premise of bullying but there wasn't much thought put into the actual scenario...