Hayate no Gotoku!

An unfortunate high school student, Ayasaki Hayate spends his days working at part-time jobs to support his extravagant parents. After incurring a debt of 150 million yen, they disappear, and Hayate was left holding the bag. Whilst running away from the debt collectors, he tries to kidnap a girl for ransom (however, the girl misunderstands his intentions and thinks he is confessing his love to her). Almost immediately, he botches the kidnap attempt but then manages to save her from other kidnappers, causing her to fall in love with him. The girl, Sanzenin Nagi, is actually the daughter of a millionaire family. In recognition of his services, she hires Hayate as a resident butler and even pays off the debt collectors.

This is how Hayate becomes a combat butler. In order to serve and protect his mistress, Hayate's life-or-death butler life begins.

(Source: AnimeNfo)