One day, Yui and Kou, who are childhood friends and lovers, have sex in the club room.
However, Yui who is threatened by the metamorphosis teacher who was watching it for that reason and forgives her body on condition of stopping.
At first, Yui was disgusted by being fucked by someone other than Kou, but she gradually began to feel pleasure in her body.
She will eventually be trained by her pervert teacher even in the secret hole behind her that she has never touched her boyfriend.
