After his uncle's marriage, 18 years old Yamada Ryosuke decided to move out from his uncle's house where he lived for five years after his mother's death. Deciding to go back to his parents' house which has been empty for years, he was surprise to find out that a girl has been occupying the old house. With the girl insisting she is a legal tenant and refusing to leave, Ryosuke could do nothing but share the house with her leading to a cohabitation (?).