The Japanese publisher Media Factory is announcing on its website that an anime adaptation of Hajime Taguchi's Kono Naka ni Hitori, Imōto ga Iru! (One of Them Is My Younger Sister!) light novel series has been green-lit.

The story centers around Shōgo Mikadono, the son of an industrial magnate named Kumagorō Mikadono who passed away. As a final wish, Kumagorō gave Shōgo a condition before Shōgo can inherit the family legacy — find a female mate at school. Shōgo transfers into a school to fulfill that condition. However, he learns that he has a younger sister who was separated at birth. He does not know what his long-lost sister looks like, but she happens to be one of the students at his new school.

Taguchi launched the light novel series last year, and the fifth volume shipped in August. CUTEG (Kokoro Connect manga) illustrates the light novel series, while Mottun* has been adapting the light novel series into a manga (with the subtitle Who is Imouto?) in Media Factory's Monthly Comic Alive magazine since May.