Daisuke Aoki, a 23-year-old bespectacled elementary school teacher at Futatsubashi Elementary School, navigates his role in class 3-1 with a good-natured yet inexperienced demeanor. His uneventful upbringing—marked by academic and athletic achievements, including university track and field as a substitute—contrasts with his emotional reticence, rooted in an unrequited university crush on a peer who married a senior. This hesitation lingers, fueling self-doubt in relationships.

Assigned to a class distrustful of his predecessor, Nakamura, he grapples with unruly students and his own inexperience. Eight-year-old Rin Kokonoe, an orphan, complicates his efforts with her manipulative tactics and overt crush. Though initially unsettled by her advances, he grows protective upon learning her background, blurring professional boundaries as he balances empathy with restraint.

Colleagues shape his growth: Sae Shirai challenges his unconventional methods, while Kyōko Hōin offers guidance, her subtle romantic interest unnoticed by him. His obliviousness to social cues extends beyond Rin, mirroring his unresolved insecurities.

Critical moments deepen his bond with Rin. A confrontation forces him to confront an attraction he dismisses as paternal, escalating when he temporarily moves in with Rin and her guardian, Reiji Kokonoe, to mend their fractured dynamic. Shirai’s intervention prompts his departure, but a revelation sparked by student Mimi Usa compels him to acknowledge his feelings. He vows to suppress them until Rin turns 16, a pledge honored in a time-skip conclusion that reunites them romantically upon her adulthood.

Prone to overthinking and emotional sensitivity, Daisuke habitually sacrifices personal clarity to appease others. Students like Kuro Kagami mock his inexperience, particularly his virginity, yet his journey from idealism to measured empathy reflects gradual resilience. His dedication to students remains unwavering, anchoring his evolution despite romantic and professional turbulence.