One morning, university student Hinamori wakes up butt-naked hugging his best friend, Tachibana. What's worse: the fully composed Tachibana says, "You were so cute last night," along with other suggestive stuff, putting Hinamori into full panic mode! From that day on, no matter how desperately Hinamori holds off from crossing that last line, the natural super sadist Tachibana starts mounting relentless attacks...?!