Read more about Hayate Yagami at: Wikipedia

Official Site: Geneon Entertainment

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.

A's opens with Hayate sleeping in her room on the night before her birthday as the Book of Darkness on her bookshelf activates, summoning the Wolkenritter. Though Hayate is an orphan, she gets an allowance from her father's friend and lives with the Wolkenritter, whom she tells civilians are her relatives. Though she is their mistress, she sees herself only as their friend (sometimes referring to them as her "kids"), and has a good relationship with them—especially Vita, who reprocically devoted herself for her to a fault. Hayate also befriends Suzuka Tsukimura, who is, unknown to the Wolkenritter, one of Nanoha Takamachi's best friends. Hayate asks the Wolkenritter not to fight anyone, only wanting to be a family with them and for them to get along with each other. The Wolkenritter initially comply, but after a few months, they realize that the Book of Darkness is sapping her mana to fill its pages, and that if they do not fill it with the mana of others, it will continue stealing Hayate's mana and potentially kill her. The Wolkenritter decide to keep this secret from Hayate, knowing that she would not approve fighting for her sake, and decide not to kill anyone to get it.

The Wolkenritter, especially Vita, are determined to save Hayate even if it means going against her wishes. However, what the Time-Space Administration Bureau (TSAB) knows that they do not is that the Book of Darkness, once completed, may stop sapping her Linker Core for pages, but that does not mean that it will stop hurting her or undo its damage. In fact, the master of the Book dies upon its completion. Just before said completion, Suzuka brings Nanoha and Fate to the hospital as a surprise visit, and encounter the Wolkenritter there. The warring groups recognize each other and their shared wish at once, and meet on the roof of the hospital. Nanoha and Fate try to tell the Wolkenritter about what will happen to Hayate, but their confrontation is cut short by both the interference of two masked men and the completion of the Book of Darkness with the Linker Cores of the Wolkenritter themselves.

Hayate Yagami has not been a contender in any CBUB matches.