Hayate Yagami (八神 はやて, Yagami Hayate?) is one of the main characters of Magical Girl Lyrical Nanoha A's, though she appears in neither the previous series Magical Girl Lyrical Nanoha nor the original alternate story Triangle Heart. She is voiced by Kana Ueda in a strong Kansai dialect. Hayate is a cute, kind-hearted orphan in a wheelchair who is actually the mistress of the Book of Darkness and the Wolkenritter (Signum, Vita, Shamal and Zafira) but is unaware that they are causing harm to other people.
Hayate's magic works slightly differently than that of Fate or Nanoha, in the fact that the closest thing she has to "familiars" are the Wolkenritter and her "weapon" is the Book of Darkness. She uses a mix of the Mid-childa and Belka styles, but in the manga, identifies herself more with the Belka side.
Read more about Hayate Yagami: Hayate in A's, Hayate in The Manga, Hayate in StrikerS, Powers