Shiunji-ke no Kodomotachi

The Shiunji family with their seven children reside in a mansion within Tokyo’s Setagaya ward. The eldest son, Arata, is tired of being pushed around by his five sisters and daydreams of a life without them. That is, until Arata’s father reveals a shocking truth—Arata isn’t biologically related to his sisters! The siblings’ relationships will be tested as they navigate life in this new light.
(Source: Crunchyroll)