It's a mistake, but I can't stop. This is a sinful BL drama between a former student who's rampant when it comes to sex and a beautiful teacher who's fastidious and serious. They drown together, knowing it's wrong...

"My former student comes for sex once a week." Shiratori, a high school teacher, has always lived his life in a way to not make mistakes, to live correctly. There's just one thing that he does that he knows is wrong, but he can't stop it no matter what. And it's sleeping with his former student, Kousaki. Shiratori can't forget the pleasure that tries to break him out of his correctness, so even though he wants to leave, he can't. But one day at school, he hears a rumor about Kousaki...