A brother's fate changes instantly upon gaining a cute little sister. He finds himself drawn into a forbidden relationship. For some reason, the sister strongly desires her brother. Seeing her sleeping in just a camisole, his reason collapses completely. Though his mind screams "This is wrong," he's overwhelmed by uncontrollable urges. Hearing her whisper, "Big brother, it feels so good," he realizes there's no turning back. Forbidden feelings begin to bloom, and their relationship rapidly deepens.