Ryota Sato and Chika Koizumi have been close friends since early childhood, even making a pinky promise to marry each other when they grew up. Now in their fifth-grade year of elementary school, they find themselves together in class 5-2 alongside a group of familiar classmates. The story follows Ryota, a kind but not particularly intelligent boy, as he navigates the everyday ups and downs of school life with his friends, including his best friend Koji Imai, the calm and intelligent Tsubasa Kawai, and several female classmates.

While Ryota remains somewhat naive about relationships between boys and girls, he has an unfortunate tendency to unwillingly end up in awkward and often compromising situations. These misunderstandings frequently lead to him receiving a beating from Chika or the talkative and active Yuki Asano, who has a crush on Koji despite being a terrible cook. The other female classmates include the quiet and mysterious Kazumi Aihara, who keeps an observational diary, the sporty tomboy Natsumi Hirakawa who refers to herself with masculine pronouns, and the glasses-wearing Megumi Hidaka who worries about maintaining her weight.

The OVA consists of four episodes that adapt most of the original manga chapters, structuring the narrative around short segments or periods that depict specific events from the characters daily lives. These episodes cover typical elementary school activities such as library visits, physical education, class time, and lunch breaks, but consistently place Ryota in embarrassing situations through misunderstandings, pranks, or sheer bad luck. One notable segment included in the OVAs but not found in the original manga is a fifth period titled Invitation featured in the second episode. The OVAs also contain a special audio track where the voices of the female characters are replaced by members of the idol unit Sweet Kiss.