Thread:KingCannon/@comment-7218858-20170706023832/@comment-25501246-20170708204445

Fanbase alone doesn't define canon, though. That's mostly the author.

Illegals is a spin-off written by a completely different author. Plus, it's not like everybody that reads MHA reads Illegals as well.

If the Illegals show up in the manga, then they're canon. Otherwise, they're not.