Just as she was pregnant with her daughter Riko, the man she was dating at the time, who was supposed to become her husband, stopped contacting her. She worked hard for the past 10 years so that her daughter would not have to struggle because of being a single mother. Her daughter graduated from university, got a job, got married, and a bright future was waiting for her. Then, one day, she unexpectedly had a relationship with her daughter's boyfriend. Despite her love for her daughter, she was unable to control the desires she had been suppressing, and she was overcome with a numbing pleasure as an electric current ran through her body...