Board Thread:General Discussion/@comment-27140233-20151109022617/@comment-11051098-20151116084828

Characters that Kubo did not make are of course filler. Nevertheless it's different with Ashido Kano. Fine, he wasn't in the manga because Kubo had to skip it due to time restraints, but unlike filler characters he did not make, Kubo did make Ashido and he was supposed to be in the manga.

You could argue that this means that all the Zanpakuto spirits in the Zanpakuto Rebellion arc are also canon because Kubo designed them, but as far as I know, Studio Pierrot made the story and everything in that arc except the character designs.

I don't know if Kubo made the story and everything regarding Ashido, I assume he did since he intended to put it in the manga, but someone else have to confirm whether or not that's the case. But if this is the case, then Ashido is indeed canon as far as I am concerned.