Yuji is living with his older brother Takashi and sister-in-law Mao after the death of his parents, helping raise his younger brother. The three of them have been living together in a peaceful household. However, their daily lives begin to change drastically after a certain incident. Hidden emotions and unspoken troubles between Mao and Yuji gradually draw them closer, leading to a forbidden relationship. As their bond deepens, complex feelings and tangled family dynamics unfold.