Reiko Shimura, a milf who lost her husband, lives with her stepson, Manjiro. One day, Manjiro's friends Mori and Shinomiya visit and secretly harbor feelings for Reiko. Sensing Manjiro's longing for maternal warmth, Mori suggests playing the role of his mother for a day. Yielding to Mori's aggressive desires, Reiko ends up having sex with him. Soon, Shinomiya joins them, and Reiko becomes immersed in passionate encounters with the two boys. A taboo threesome unfolds as forbidden desires spiral out of control.