Kenji, the second son of three brothers, always felt like an overlooked child in his mother Saki's eyes. But one spring, everything changed—his older brother moved out for work, his younger brother entered a boarding school, and their father began living separately due to a job transfer. Suddenly, Kenji and Saki were left alone together in the quiet family home. The once lively household fell silent, and Saki began to feel loneliness and a deep sense of loss. Seeing his mother's sorrow, Kenji grew resentful of the past when his brothers had monopolized her attention. Driven by emptiness and longing, he began craving his mother's affection exclusively for himself, setting the stage for an intimate, forbidden bond between mother and son.