Michi and her family have recently moved into the Happiness House, a massive tree featuring various small structures built both on and within it. While exploring her new bedroom, Michi discovers a peculiar, nut-shaped object. Shortly thereafter, a strange creature named Nanami-chan hatches from it. The pair quickly become close friends. Together, Michi and Nanami-chan discover all sorts of new things, and each day they encounter more eccentric residents of the Happiness House.