The Zanpakutō Rebellion was conceived as an Anime-Only arc which was used to give Tite Kubo more time to write the Manga for them to adapt and simultaneously keep people watching bleach. Anime-only arcs are known to take great liberties within the story and background. Masaki Kurosaki was revealed to be a Quincy within the Manga long after the creation of the Zanpakutō Arc. Muramasa and his abilities are not considered Canon within the Bleach universe as he conflicts too much with the established, original manga material and timeline.