Boku datte Kimi ga Inakerya Tabun.

When Shion transferred schools, he immediately became the new target of bullying. Leo saw how Shion was bullied and stripped naked, and upon seeing Shion's private parts and feeling desire grow inside him, he decided to help the new boy.

Ever since then, the two of them have always been together. Naturally they entered the same university and decided to live together. Leo had always been possessive and dominant, and his desire for Shion's soft private parts never lessened. Shion never minded, but upon confronting Leo about their romantic relationship, it comes to light that Leo never thought of it as such...! Is it only Shion's private parts that turns Leo on!? This comic is a world in true Tsutako Tsurusawa style, with a serious arrogant guy together with a shy shut-in, dealing with one naughty fetish.

(Source: Renta!)