The brother of this guy used to have Tsukasa Aoi as a girlfriend. The thing about the brother is that he was a well-known womanizer and whore-goer, so he passed all that knowledge to the girlfriend Aoi. But nowadays they are not together anymore, and this guy quickly realizes that she is a full-blown slut. So the question that remains is, will he cross the line and go where his brother has been before?
