Two boys meet during the summer of their third-grade year. Tsubasa is quiet and serious, while Gyotaro is a cheerful genius whom everyone in the class looks up to. Despite their differences, they form an intense and close friendship, sharing irreplaceable moments within their own small world. However, jealousy and a small incident driven by misunderstanding suddenly tear their relationship apart. The story then leaps forward in time, spanning more than thirty years as the two boys grow up and their lives go in completely different directions. When memories from their shared past resurface, they are forced to confront what truly happened between them all those years ago. The narrative follows their eventual reunion and a contemplative journey that gently explores themes of memory, the meaning of life, and the lingering impact of a friendship broken and possibly mended.