Sumino, a first-year high school student, enrolls in a prestigious soccer school in Kamakura but breaks his leg soon after joining the team. Unable to practice and feeling adrift, he spends his days wandering aimlessly and his nights partying. One day, he meets Aoki, an older man who works at an izakaya, and gradually begins to experience emotions he has never felt before. This is a story of an unforgettable summer, both the worst and the best.

The narrative is split into distinct geographical and emotional arcs. The first part of the story is set in the coastal city of Kamakura, where the initial connection between the injured teenager and the older izakaya worker forms. The atmosphere in Kamakura is one of fleeting, wistful moments as Sumino navigates his injury and his emerging feelings for Aoki.

The story then moves to a Tokyo arc. Here, the atmosphere shifts as Sumino must confront his feelings in a new, more anonymous urban environment. A significant figure in this arc is Aoi, a character described as out and proud, who serves as a contrast to Sumino's internal confusion. Aoi represents a form of self-acceptance that Sumino has not yet achieved, highlighting that the core of the story is Sumino's journey toward accepting himself.

The central relationship is marked by ambiguity and miscommunication. Sumino often misreads Aoki’s actions and expressions. For instance, he interprets Aoki's interactions with his teacher and with Aoi as romantic, while a reader may see those interactions differently. The story does not provide easy answers or a conventional romantic development, focusing instead on the rawness of the characters' feelings and the painful reality of unspoken desires.

The manga concludes with a significant time jump, showing Sumino and Aoki as old men. The ending is deliberately cruel and bittersweet, suggesting that Sumino finds a measure of contentment simply in knowing that Aoki remembers the time they spent together, even if their relationship never developed beyond those summer memories. The focus remains on the indelible mark that one person can leave on another's life, for better and for worse.