Since her father’s death in elementary school, Kamura has become the responsible one at home, cooking, cleaning, and even waking her mother for work. She promised herself she would always protect her mother, and she has held to that duty for years. But that quiet, controlled life is upended when her mother announces she is getting remarried. Kamura is stunned to learn that her soon-to-be two‑years‑older stepbrother is the same homeless young man she saw on the streets the day before. His name is Gyou, and he is elusive, unsettling, and impossible to read. Meanwhile, her friend Youhei, who has always teased her and made her feel foolish, begins to act in ways she does not expect—offering comfort and stirring feelings she cannot easily name.

The story is set in everyday high‑school and home life, where the ordinary becomes charged with new tensions. Kamura must navigate the arrival of a stepfather and an unfamiliar brother, all while wrestling with her own buried feelings about responsibility, care, and what it means to let go. As she grows closer to Gyou, she discovers he carries a painful past involving his older half‑sister Tsukina, a relationship that ended in an accident and a vow never to see her again. Yet Tsukina eventually reappears and transfers into their town, forcing old wounds open again. The narrative follows Kamura, Gyou, Tsukina, and Youhei as each character’s feelings collide and evolve across four interwoven arcs. Kamura struggles to accept her new family and to release the weight of being her mother’s sole protector, while the unresolved bond between Gyou and Tsukina casts a long shadow over the growing romance between Kamura and her stepbrother. The story resolves as the four of them must each decide where their loyalties and desires truly lie.