Yuuta Segawa, a college student, suddenly becomes the guardian of his three nieces in place of his sister and her husband. The eldest niece, Sora, is a 14 year old middle school student with semi-long brownish hair decorated with a ribbon. The middle niece, Miu, is an elementary schoolgirl with blond pigtails.

The youngest niece, Hina, is an angelic 3 year old attending daycare. This at-home romantic comedy illustrates the chaotic but heartwarming lives of these four characters in their tiny one-room apartment.