Hayate no Gotoku!

Hayate Ayasaki's life wasn't great, but when he loses the job he used to support his good-for-nothing family, and his deadbeat parents sell him to the Yakuza for cash, it really hits rock bottom! Faced with having to pay off the huge debt before he's converted into black market organ parts, a desperate Hayate decides to kidnap oddball heiress Nagi Sanzenin for ransom... but when even that goes wrong and he accidentally ends up rescuing Nagi from other kidnappers, it turns out that Hayate is the bodyguard that Nagi has been looking for! So now he's the Sanzenin family's butler, and… maybe… it might be the start of a potential romantic relationship… assuming Hayate can survive the on-the-job training, of course.

(Source: Sentai Filmworks)