Manga by author Murata Kouji - Status ongoing

Having forgotten his keys, Tamao Hiroi a high-school student, returns home using the back entrance and is surprised to find a stranger in his bed Soon he realizes this is no stranger but Ran Homura, one year younger, softball ace and one of the most beautiful girls at school! Hiroi watches her masturbating on his bed and instinctively does the same peeking through the glass door. He is soon found out though and a strange 'master/slave' relationship begins!---

Katsutoshi Umiyama is a young teacher of 25 years who is designated as responsible for the men's club volleyball school. The women's club, however, is in the hands of the beautiful Maho Kawashima. When Umiyama accidentally gets too close to a club girl, Ai, the student does not seem to be upset, but ...