Kotaro is drawn to his mother Yuri, who is caring for his newborn sister. Taking advantage of her bath time, he sneaks into the changing room, picks up her bra stained with breast milk, and hungrily laps at it, overwhelmed by desire. When Yuri discovers him, she hesitates at first but then invites him to suckle as he did in childhood, pressing his mouth to her breast. Overcome by the warmth and taste, Kotaro becomes aroused, and seeing his excitement, Yuri can no longer resist—she draws close, and their forbidden bond deepens.