It's a Family Affair(2005)

It's a Family Affair is a Japanese anime series centered on Keisuke, a young man living alone with his ten step-sisters in an isolated household. As the only male in the home, Keisuke finds himself the object of his sisters' affection as they grow increasingly bold in their pursuit of intimacy with him. The series explores the escalating dynamics between the siblings as Keisuke begins to recognize and respond to their advances. Blending comedy with romantic tension, the show navigates the unconventional relationships that develop within the family unit, examining themes of desire and connection in this unusual living arrangement.