Character from Mahou Shoujo Lyrical Nanoha by Masaki Tsuzuki / Seven Arcs
The four guardian knights of the Book of Darkness — Signum, Vita, Shamal, and Zafira — ancient magical constructs who have served every master the Book has had, and who, under Hayate, became something the Book had never made before: a family.
The Wolkenritter exist because the Book of Darkness exists. They were created in the Ancient Belkan era and have served through every incident — they remember every master. Most of those masters they watched die, either from the Book's power drain or when the Defense Program completed and activated. Hayate is different. Hayate doesn't know what they're doing, and they are not telling her, because they know that if she knew she would stop them and then die. This is the tragedy of A's: four beings who are capable of love, choosing to do a terrible thing for the best possible reason, watched by the audience who can see exactly how wrong they are. After A's they join the Bureau. They are the Yagami family. They live in a house together and Hayate cooks dinner and they all come home.
Four entities with distinct Ancient Belkan Knight Armor: Signum in purple-flame, Vita in red-iron, Shamal in celadon-green, Zafira in wolf-form blue. When mobilized as a unit they are among the most powerful combinations of mages in the TSAB's operating territory.
Also known as: Cloud Knights, The Knights of the Book