The narrative of Kodomo no Jikan focuses on 23-year-old Daisuke Aoki, who has just secured his first position as an elementary school teacher at Futatsubashi Elementary. He is assigned to Class 3-1, where a student named Rin Kokonoe, who is mischievously precocious, develops a crush on him and even declares herself to be Aoki's girlfriend. She aggressively pursues her goal of being with her teacher, despite the risk that he will lose his job if she gets too close. This situation is further complicated by the often complex, intertwining relationships among them and their respective friends, families, and peers.