My Girlfriend Cheated on Me with a Senior, so I'm Cheating on Her with His Girlfriend

Yuu Isshiki, a first-year college student, has a charming girlfriend, Karen Mitsumoto. However, one day Yuu discovers that Karen has an adventure with her Senpai, Kamokura Tetsuya. Angry, sad and desperate, he calls Kamokura's girlfriend, Sakurajima Touko, from which she is said that she is the most beautiful girl in the institute. "Touko-senpai. Please, have an adventure with me. " But Touko said: "I can not let me fool me. I have to push my opponent at the bottom of despair. " Her's plan is then to continue falling in love and, finally, to break it as the night with another man.