After five years of marriage, Erika divorced and became a single mother raising her son, Satoshi. They moved to the countryside, hoping for a quiet life, but shy and socially awkward, Satoshi struggled to make friends and often felt lonely. For him, the only source of comfort was his mother—her back, her hips, the warmth of her presence. Erika, too, began to notice something new: whether doing housework or lying asleep, she became aware of her son’s small hands gently touching her buttocks, awakening in her an unfamiliar tenderness. Gradually, their mother-son bond deepens in unexpected ways, blurring boundaries and evolving into a strange, intimate relationship.