Sumire, the second wife of Kanazaki Koichi (Rich Dad), lives a wealthy and happy life, but is troubled by her relationship with her stepson Takashi and her sexual life with her husband. Meanwhile, Takashi is tormented by his young and beautiful stepmother Sumire. One day, Sumire is embraced by Yamamoto Shigeo (Poor Dad), an ordinary employee at Koichi's company, who exploits her Kokoro weakness and makes her fall in love with him, becoming addicted to his techniques. Takashi also sees through his own lust and becomes fascinated with Shigeo's "sex philosophy". After that, Sumire and Takashi start having a physical relationship...