Gorou Hoozuki is still hopelessly infatuated with his sadistic older stepsister Haru, whose teasing has turned openly suggestive now that neither of them pretends the crush is a secret. This sequel to Hoozuki-san Chi no Aneki, set a couple of years on, adds Haru's cousin Aoi, a year younger than Gorou, who moves in and settles into the household as the little sister of the title. Domestic chaos and mixed signals carry the gags as the three work out their new arrangement.