Azusa Noyama, a 12‑year‑old fifth‑grade student, is universally known by the nickname “Azuki‑Chan,” a name she dislikes. When a new student, Yuunosuke Ogasawara, arrives, he asks her about the nickname and expresses his fondness for it. Intrigued, Azusa develops feelings for Yuunosuke, and they begin dating. The two share a diary and grow close as boyfriend and girlfriend.