Gakuen Tengoku - Sore wa Koi desu Koizumi-kun体操服を脱がさないで ; Taisoufuku wo Nugasanaide

A boy wearing a facade of a pristine angel, Koizumi-kun, and the class’s disliked Kashihara-kun, and their changed relationship since the day they had sex. This popular pair was introduced in “High School ☆ Lullaby