DASS-579 — My Girlfriend's Mother Is More Appealing To Me Than My Girlfriend, And My Dick Is So Hard It Hurts.

Sakai and Kokoro are a couple. One day, Sakai goes to her house to play and meets Aiyu, a busty mother with an emphasis on her busty figure, and becomes excited. When Sakai uses the bathroom in her house, he witnesses Aiyu masturbating while pretending to be Kokoro and calling out his name. Seeing this, Sakai is unable to contain his excitement and masturbates his erect penis, but Aiyu climaxes first, leaving him with indigestion. Sakai can't get this incident out of his head, and he pressures Aiyu into a relationship...