Gakuen Tengoku - Sore wa Koi desu Koizumi-kunGakuen Tengoku - Sore wa Koi Desu Koizumi-kun; 学園天国 それは恋です小泉くん

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