Iku Iku ♡ Succubus Saikyouiku: Rakudai Inma no Koukan Ryuugaku Nisshi

Based on the erotic game by DWARFSOFT.

Busujima, a middle-aged teacher with an insatiable sexual appetite, is sexually harassed just for watching a female student at a club activity, and is summoned to the school principal. During the lecture, a mysterious door suddenly opens, and a girl who looks young but has enormous breasts comes out...