The Shiunji family with their seven children reside in a mansion within Tokyoโs 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 Arataโs father reveals a shocking truthโArata isnโt biologically related to his sisters! The siblingsโ relationships will be tested as they navigate life in this new light.