Kaito, the youngest of three brothers, was always seen by his mother Kiyoka as a quiet child who struggled to assert himself. However, one spring, his older brothers moved out to live on their own, and his father began living separately for work. Suddenly, the once lively household fell silent, and Kiyoka became overwhelmed with a sense of loss. Witnessing her loneliness, Kaito felt both sadness and regret, prompting him to take action to reclaim the motherly affection he had never fully possessed. As the two begin living alone together, Kaito's emotions grow deeper, blurring the boundaries between mother and son.