After their parents' death, the older brother supported his life through part-time jobs, while his sister comforted him with a "pretend game." One day, their uncle visited the house and attacked the sister. Threatened with, "If you just listen, no one has to suffer," Mikako was unable to resist and was forcibly impregnated. Afterwards, the brother witnessed his sister, who had been trained into a frenzied mating female, experiencing intense sex repeatedly, reaching climax numerous times in her debauched state.
