After her husband passed away, Hijiri had to raise their daughter on her own. She always wanted her daughter to study hard so that her husband could rest in peace in heaven. However, in the past three months, Shoko's grades kept dropping, coinciding with the time when she started dating Kiyoshi. To make matters worse, Shoko discovered that Kiyoshi was cheating on her with another girl. Since then, Shoko lost interest in studying, feeling sad and discouraged all the time. Blaming Kiyoshi for Shoko's change, Hijiri decided to punish him by... having sex with him! She called Kiyoshi to her house, pinned him down, straddled him, and ruthlessly slammed her big butt on his penis without mercy. She used her vagina to suck up all of Kiyoshi's sperm, making him ejaculate into her vagina repeatedly. She forced him to treat Shoko well, or else Hijiri would continue to "punish" him. But because it had been a while since she last had sex, Hijiri's sexual desire was unleashed. Even though Kiyoshi was still treating Shoko well, she still wanted to "punish" him. She became addicted to having sex with her daughter's boyfriend, and they constantly had sex whenever they could. Until one day, Shoko came home and discovered everything...