Yui Suzuhara, the association was done secretly with Protagonist who was the class homeroom teacher. However a certain day, Yui is called by gym teacher Tougou, the photograph of the date early morning with secret Protagonist is shown by anyone and it is threatened.

If it is exposed by everyone, it becomes Protagonist and separate.

[Because i do anything as it says...]

"Anything" Because it is young, Yui who doesn't understand the true meaning, Tougou is promised so. And Togo forces a sexual act without paying attention to confused Yui.

For the sake of Protagonist though it is thought it is strange, but a body remaining it is developed. And to Yui from who the appearance becomes strange little by little, protagonist gradually holds distrust...