One day, mother Shoko opened her son's room door to collect laundry, only to find him masturbating on his bed. Surprised, she saw him stimulating his erect cock with his hand. Their eyes met briefly, but she could do nothing but silently close the door and leave. After that moment, the awkwardness and the lingering image of her son's penis haunted her mind, leaving an unshakable discomfort deep within her heart.