In order to let her son Koichi go to a national university, her mother, Yuna, has been raising her strictly since she was young. If her grades dropped even a little, she would scold her with piercing words and make her spend her days immersed in her studies. Koichi begins to feel anger and hatred toward such a mother, and plans a plan. It was to tie up and rape her mother when his father was away on a business trip.
