WAIT what if this is actual time travel and Makoto is the one that writes the message on Akira's board thus making her the mysterious M.M. - and she writes it like that so that it doesn't interfere with the timeline, even though it means Makoto Miyamura instead of Maya Macaronni.
More importantly, what if we're into a bootstrap situation where all the changes they'll make in the timeline have already been done in the original timeline, we just didn't realise it was them that did them?
Do I think this is true??! no. but it'd be cool lol