Akai Miki, the mother of three children, once had a bustling household. But everything changed one spring when her eldest son moved out for work, her youngest entered a boarding school, and her husband began living separately for his job. The house suddenly fell silent, leaving Miki overwhelmed with a deep sense of loss and emotional unease. Her second son, Kenji, always the quiet and undemanding child, noticed his mother's growing loneliness and emotional fragility. As he felt the absence of his siblings more intensely, he struggled to understand his own emotions, gradually seeking his mother's affection for comfort. Amid this shifting dynamic, the bond between mother and son takes an intimate turn, blurring boundaries as Kenji wrestles with his feelings and steps into adulthood.