Tatsuya, the second son of three brothers, was seen by his mother Yumi as a quiet and unassertive child. One spring, his older brother began living independently for work, while his younger brother started attending a boarding school on a sports scholarship. As a result, their father began living alone for his job, and the household suddenly lost its liveliness, leaving just mother and son living together. Facing this change, Yumi struggled with a sense of loss. Witnessing her loneliness, Tatsuya began to desire the motherly affection he had never fully possessed. The once quiet days took a sudden turn, as new emotions stirred within him.