Sayu Ogiwara, a 17-year-old runaway from Asahikawa’s affluent Ogiwara family, escapes a life of emotional neglect and favoritism toward her older brother Issa, heir to their prominent food corporation. The suicide of her bullied friend Yuuko Masaka, coupled with her mother’s blame, fractures her already strained home life, propelling her into a six-month existence of trading sexual favors for shelter under aliases like "Miyuki." Her appearance—medium brown hair, hazel eyes, and a youthful yet mature F-cup figure—cloaks a duality of playful flirtation and fragile self-loathing, her survival tactics masking deep-seated vulnerability.

When Yoshida, a 26-year-old salaryman, offers shelter without demanding intimacy, Sayu tests his motives with seduction, distrusting altruism. His refusal unravels her transactional worldview, fostering reluctant trust as their bond evolves into a familial dynamic, Yoshida guiding her to confront her past. Allies like Airi Gotou, Yoshida’s forthright boss, and Yuzuha Mishima, a coworker with shared runaway experiences, push her toward self-reckoning, while friend Asami Yuuki rebuilds her fractured social confidence.

Forced home by Issa’s intervention, Sayu negotiates two final weeks with Yoshida before facing Hokkaido. A mediated reconciliation with her mother remains tense, yet she graduates and mends ties, retaining Tokyo connections. Two years later, a lamppost reunion with Yoshida marks her transition from traumatized survivor to self-reliant adult, her journey underscoring the weight of empathy, the scars of familial rupture, and the slow reclamation of agency beyond survival.