Hayate the Combat Butler Vol. 1 (manga)

Hardworking Hayate has a plan to pay back the yakuza--who are now the legal owners of his body parts: he'll kidnap someone and ransom them for a mountain of money! But things get tricky when his would-be kidnappee--who as luck would have it is the daughter of a mind-bogglingly wealthy family--mistakes Hayate's actions for a confession of love, and subsequently hires him to be her personal servant. At least his employment future is secure, or so he thinks...