I suspect we'll find out the specific reason Mameyama didn't tell Maya she was coming to Tokyo just for the day next chapter.
I suspect it's something like she was seeing a medical specialist that they don't have where Mameyama lives, which I think might be Aomori City, and she didn't want Maya to worry about her condition.
EDIT: Oh, essentially what @Euro_PURO said. I had this comments window open for an hour while I was doing other things and didn't think of refreshing.
Damn, I can relate to Maya's mundane yet anxiety-inducing dream. There something uncomfortable about dreaming of situations you usually experience in real life that you can't distinguish it from reality even more so than other dream situations.
@SasazukaIchimashi Seems strange that she would tweet out where she was if she wanted to keep it from Maya then. Unless this was simply a lapse in her judgement.