Aoki Daisuke, a 23-year-old teacher, takes charge of his very first class, a group of third graders, and immediately gets off to a bad start with all of them. One small act of kindness is enough to win over Rin Kokonoe, a precocious and mischievous pupil who promptly declares herself his girlfriend. From then on she is set on winning him over, or getting him fired if that comes first. Aoki has to work out what Rin really wants and whether he can help her with it. He is also trying to learn what happened to Usa Mimi, a friend of Rin's who has not yet come to school. The show mixes comedy, drama and ecchi material and is adapted from a seinen manga by Watashiya Kaworu.