Hayate Yagami

A sweet and gentle orphan who is confined to a wheelchair, is cared for by the Wolkenritter, who deliberately keep their battles hidden from her. She knows that completing the Book of Darkness would grant her immense power, but she refuses to accept that power at the cost of innocent lives. Unbeknownst to her, however, the Book is already feeding on her life force, causing her paralysis and slowly weakening her. If it is not completed, the Book will eventually consume her life entirely.