Onegai Mr. Idol

A scary debt collector suddenly appears at the home of Haru, a high school girl and the daughter of a small talent agency. In order to help Haru, who is about to lose her home due to her father's debts, her childhood friend and roommate, the super handsome Toru, becomes an idol and takes over the debt for her. Toru gets a promise from the grateful Haru that "Once you've paid off your debts, I'll do anything you ask of me," but...?

(Source: Shueisha, translated)