Shun Hashimoto, a Japanese novelist from Hokkaido, relocated to Okinawa after his family rejected him. This rejection occurred when he revealed his homosexuality during his wedding ceremony to childhood friend Sakurako, causing their arranged marriage to collapse. Earlier homophobic experiences in high school, specifically when classmate Wada discovered Shun's attraction to him, had already intensified Shun's internalized homophobia and struggle for self-acceptance.

In Okinawa, living with his aunt Miyako, Shun observed Mio Chibana, a frequently solitary high school student, by the beach. Despite Mio's initial reluctance, a connection formed between them. This developing relationship halted when Mio left for the mainland to enter an orphanage following his parents' deaths. Three years later, Mio returned at age twenty and confessed his love. Burdened by guilt over potentially denying Mio a conventional life and still wrestling with self-acceptance, Shun repeatedly urged Mio toward relationships with women. Shun's resistance stemmed from deep-seated fears of societal rejection and internal conflict about his identity.

Sakurako then arrived in Okinawa, informing Shun of his father's illness and urging his return to Hokkaido. After a violent confrontation where Sakurako attacked Shun—prompting Mio's intervention—Shun agreed to visit his family. He asked Mio to accompany him, marking a pivotal step toward accepting both Mio's support and his own sexuality. This decision initiated Shun's emotional healing, aided by Mio's steadfast affection challenging his negative self-perceptions.

In Hokkaido, Shun and Mio moved in with Shun's parents. Shun encountered Fumi, his younger adopted brother, who was initially enthusiastic but later became rebellious and occasionally disrespectful during his teenage years, using derogatory terms. Shun's relationship with his father remained strained and distant initially, though his mother welcomed him warmly. Over five years, Shun published a successful debut novel that earned a prestigious award but subsequently faced creative exhaustion, leading to unemployment. He became increasingly withdrawn, neglecting household responsibilities and his relationship with Mio, with their intimacy diminishing significantly.

Recognizing the toll their living situation took on Mio, Shun agreed to relocate with him to Tokyo. This move symbolized a continued commitment to their partnership and a new phase of mutual support. In Tokyo, Shun encountered Shintaro Kusano, a man he had briefly met years earlier during a low period when Shun sought validation through a risky encounter. This reunion triggered a strong emotional reaction.

Shun has short, messy taupe hair, brown eyes, and an often-exhausted demeanor. He typically wears button-up shirts or polos layered with cardigans or jackets, occasionally using glasses in public to avoid recognition. His personality combines bluntness with introspection; he procrastinates, works intensely to meet deadlines, and neglects self-care. While emotionally reserved to avoid vulnerability, he is capable of endearing behavior and easily flustered. His journey reflects ongoing challenges with self-worth and identity, even as he progresses toward greater acceptance and stability in his relationship with Mio.