Kotetsu Segawa, anyone who hurts Nagi, his parents
Hayate has had to work to support his parent's bad habits since the age of eight, always moving from job to job, as he is fired when he is discovered to be underage. Hayate's dad is unemployed and his mother is a compulsive gambler, which leads inevitably to their bankruptcy.
Hayate is a very selfless and generous person, always trying to help others in need even if it means causing harm to himself. He is very independent and skilled in many things, i.e being a good cook, housekeeper, and he can even identify fake works of art with one glimpse (thanks to one of his father's con jobs in the past) among many others. He has super human strength, tremendous speed, retaliation, and endurance allowing him to do things which are normally impossible. However, Hayate is rather dense when it comes to love. His poor empathy is always troubling him as he always misunderstands the feelings of people around him like Nagi's feelings toward him. This is probably because of his innocent personality and inexperience with girl's thoughts and feelings.
The characters in this series continually remark that Hayate looks poor and needy. He believes that everyone hates him, except children, though he doesn't think of children as being anything other than friends. He can also play the violin. Despite his terrible luck, Hayate lives up to the title of "combat butler" as he is proficient in repelling attacks from almost anything, including other butlers.
(Source: Hayate no Gotoku Wikia)
