Danshi Ryou Himitsu no Idol

Even though your twin brother was set to enter the show business, he suddenly disappeared?! Despite having no clue as to why, being his older sister you decide to start dressing up as him and debut in his stead. A more experienced idol from the same company and one from another, your manager, even the overbearing company president... Your exciting life at the (hot) boys' dorms is about to begin. And remember: you must not tell anyone that you're actually a girl! [Translated from official website]