The considerate sister, yui, who is good at housework, and the shy, easily influenced younger sister, karin. The two were living comfortably with their mother's remarried husband, a wealthy stepfather. However, while their mother was hospitalized due to an illness, a nightmare began... The stepfather, who had been so kind, suddenly changed his attitude, exposing his lust and advancing on the sisters. The easily influenced younger sister was skillfully led into sex. The spirited older sister was forcibly inseminated. Exploiting their differing personalities, he controlled their minds and bodies. Before they knew it, the two had become female slaves competing to serve sexually. 'Our only value is to be the stepfather's breeding sack, I'll go first, I'll go first...!' They were brainwashed to the point where nothing else entered their minds...
