When their parents married, high school student Touri Ayukawa and his new stepsister Momoka found themselves living under the same roof. While Momoka appears flawless at school as a model student admired by everyone, she hides a much different side at home. She develops an intense and inappropriate fixation on Touri, subjecting him to relentless physical advances and voyeuristic behavior that exploits their new family arrangement. Touri, a boy navigating adolescence, finds himself increasingly caught up in his stepsister's provocations. The situation grows more complicated with the introduction of Masaki, Touri's childhood friend from the athletics club, and Aina Sato, another girl whose caring attitude toward her own younger brother masks her own questionable intentions concerning Touri. The series, serialized in Comic Heaven magazine since 2019, follows this erotic comedy as the boundaries of their sibling relationship continue to erode. With multiple volumes released, the story maintains its focus on the dangerous game unfolding between the ambitious Touri and the sexually aggressive Momoka, all while other young women with their own peculiarities enter the picture.