The main protagonist of the hentai Koizumi-kun is crazy about his classmate Rin-chan, but with his perverted character and habits he does not even hold out hope for reciprocity. However, Rin herself has also been in love with our hero for a long time and only her timidity prevents her from admitting it to her lover. At some point in the series, Koizumi saves Rin’s best friend, Kumi, from being raped, as a token of her gratitude. And she, as a sign of gratitude, well, you know… What awaits our hero next, watch and find out…