Based on the erotic games by Jitaku Studio.

Shinobu Nagato has given up on being an otaku after falling in love with Kanna Miyanoue, a girl who doesn't like otaku. Shinobu is suddenly called by her to visit her classroom after school, but the person who greets him is Ayame Amasaki, a former gal... and she's masturbating on the corner of a desk! Before he can even stand being shocked by her extreme approach, the situation develops into a slightly hentai love square with Shinobu's childhood friend Yuri Satogami joining in!!

(Source: parabook, translated)

Note: Includes 1 extra chapter from the e-book limited special extended edition