Keita Toyama, the only surviving child of Tsuyoshi and Sayoko Toyama, carries the weight of a devastating family tragedy. During a car accident, Tsuyoshi’s split-second decision to rescue Keita resulted in the death of his younger sister, Sayaka, fracturing the family’s emotional foundation. Tsuyoshi’s spiraling guilt and instability manifest in a desperate scheme to "reunite" the family, forcing Keita into the center of his father’s unraveling psyche. The child’s vulnerability becomes pivotal as Tsuyoshi’s trauma escalates, culminating in a climactic confrontation at an amusement park where their lives hang in the balance. Keita’s presence during this perilous encounter underscores his role as both a survivor and a pawn in the aftermath of irreversible loss.