The Only Way We Can Become Family Even Though We Aren't Related By Blood

His step-sister Erika, whom he reunites with for the first time in seven years after their divorced parents reconciled with each other, and his childhood friend Mio, who feels like a close male friend to him despite being a girl. Katsuragi Shota ends up living under the same roof with the two of them. “...Is this what it’s like to be siblings?” “If we were really siblings, would we act like this?” The three of them, each having experienced loneliness related to family, find a comfort that feels more familial than that of strangers. However, to avoid romantic troubles at their high school, Mio and Shota decide to pretend to be a fake couple, leading them to unexpectedly become aware of each other as the “opposite sex”...!? As the three non-blood-related individuals search for a way to become a family, they navigate feelings that go beyond mere familial ties in this cohabitation romantic comedy.