By the third installment, the series had perfected its formula:
| Character | Role | Development in Vol. 3 | |-----------|------|-----------------------| | | Protagonist | Shifts from reactive (still reeling from the move) to proactive (takes initiative to help Mrs. Saito, confronts his own feelings about adulthood). | | Haru | Childhood friend (off‑panel) | Though absent physically, Haru’s presence is felt through Kaito’s flashbacks, making their strained bond a central emotional anchor. | | Miyu | Café co‑worker, aspiring photographer | Becomes Kaito’s confidante; her candid shots of the sea help Kaito see beauty in impermanence. | | Mrs. Saito | Elderly regular | Represents the “wise elder” archetype; her backstory about leaving her hometown adds a generational perspective on “growing up.” | | Takeshi | Manager of the café | More stoic than before; subtly reveals his own past as a former athlete who had to quit early, mirroring Kaito’s fear of losing his “boyhood.” | shounen ga otona ni natta natsu 3 233cee811