Until the end of summer.
One day, Yui and Ko who are childhood friends and lovers have sex in the club room.
However they are being threatened by the pervert teacher who was unfortunately watching Them.
For that reason, Yui must allows her body being used by the pervert teacher.
At first it was Yui who had a feeling of disgust for being fucked by someone other than Kou, but gradually her body began to feel pleasant.
Eventually, the secret hole in the back that has never been touched by her boyfriend will also be trained by a pervert teacher.