After the death of her husband, Chisa lives alone with her son Ayumu—until one day, Ayumu's friend Nozomi comes over and forcibly takes Chisa right in front of him. That night, Chisa peeks in on her son bathing and is shocked to see him masturbating in the tub. When she confronts Ayumu, an unexpected truth comes to light. Upon learning this secret, Chisa begins to desire something from her own son. As forbidden emotions deepen between mother and son, their taboo relationship spirals into uncharted territory.