Honor student Himari's younger sister and younger sister Hinako, who is unfamiliar at school and doesn't go to school. The two lived in peace with their mother and her remarried partner, a wealthy father-in-law. However, while the mother was in the hospital giving birth, the house was in a lewd space dominated by her father-in-law. Vaginal ejaculation is done by cleverly taking advantage of the cock's guilt. Having sex using Himari's kindness while thinking of her biological sister … One day, the two became sex slaves competing for service by competing for their father-in-law's cock. My mind and body were affected so much that I was excited and wondered who would get pregnant first.