Highschool OnimaiOnii-chan wa Oshimai! - Koukou Onimai (Doujinshi); お兄ちゃんはおしまい! - 高校おにまい (同人誌); Onii-chan Is Done For! - Highschool ONIMAI (Doujinshi)

Without being able to return to a man, Mahiro Oyama stayed as a girl since middle school and now has become a beautiful high-schooler who gets completely dominated by his first friend since the transformation, Momiji Hozuki, who has gotten really tall and became popular with the girls in their school.