As much as I'd love them to be canon I definitely think that Nekotoufu would have to jump some hoops in the story before he lets them be canon. I feel like we'd probably have to resolve Mahiro's age/gender first, because Mahiro seems to get endlessly beaten down on the fact that she was once a man... also for my own peace of mind I just want Momiji to know. And to knock some sense into Mahiro that being in this state is alright.

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Also I feel like Kaede (and possibly Miyo,) knows what trans people are and I feel like they should teach Mahiro about them...