After losing her husband, Izumi struggled to support her two sons through part-time work and side jobs. Though money was tight, their home was filled with smiles and warmth. The close-knit family enjoyed nightly mixed bathing together, but one day, the younger son suddenly became physically aroused, drastically changing the atmosphere. Yet, driven by deep maternal love, Izumi gently caressed her younger son, genuinely overwhelmed with affection for him. Witnessing this, the older son also gradually found himself drawn into a forbidden relationship.