Imasugu Onii-chan ni Imouto da tte Iitai!

Rikuto now has a younger sibling, Ayumu, following his father's remarriage. Unbeknownst to him, Ayumu is a girl ordered by her mother to pose as a boy. Rikuto grows increasingly fond of his charming younger brother, while Ayumu struggles with concealing her true identity. As spring begins, both attend Asaoka Academy, a private school where Ayumu is finally allowed to present as a girl. Rikuto befriends several classmates, each dealing with personal identity issues. His childhood friend Matsuri has distanced herself from her femininity, Mao, though female, regularly dresses as a boy, and the timid class representative Kimika wants to change who she is. With Ayumu's support, Rikuto aims to help them rediscover what they feel is missing.