Hanabi Ayase, a spirited sixth-grader with pigtails and wide-eyed innocence, thrives within her inseparable trio of friends—Yui Aoi and Marin Ogura. Her life shifts when a classroom music pairing with Yuuto Takao sparks unexpected affection, culminating in a rooftop kiss that cements their status as the class’s inaugural couple.

Her guileless nature clashes with Cocoa Hamana, a classmate whose saccharine facade masks calculated efforts to destabilize Hanabi’s relationship, driven by Cocoa’s self-proclaimed compatibility with Yuuto. Meanwhile, the reappearance of childhood companion Ayumu Tsutsumi complicates Hanabi’s loyalties as he openly pursues her, forcing her to navigate Ayumu’s advances while reaffirming her commitment to Yuuto.

Amidst this, Hanabi confronts the turbulence of adolescence: bodily changes, fears of parental disapproval, and the delicate balance of young romance under peer observation. Her journey traces a path from wide-eyed naivety to sharper emotional awareness, though her earnest heart remains unguarded.

Later trials—miscommunications, rivalries, and public disputes—strain her bond with Yuuto, pushing Hanabi to cultivate resilience and articulate her feelings. These obstacles underscore her maturation as she learns to shield her relationship from external pressures while preserving its fragile authenticity.