Maya started showing up to tutoring lessons way after Noriko. If she was with Akira before Sekai's death it would make no sense for her to show up later. In fact, given that she meets Akira after running away from home, it would mean she'd be living in the Arakawa family home, which wouldn't make sense either with her later moving to the tutoring place.
Edit: Your older post makes sense, but I'm not convinced by it. I mean, I'm not convinced by it without a supernatural interference that puts a Maya there. If that's the case then I'm onboard.
Basically I don't think having Maya in his life fits the Akira that was in a relationship with both Sekai and Niki. If that wasn't an 8 year old though, and instead was a conjured up narrator Maya, then I'm cool with it.
This
can be solved by hypothesizing a few scenarios without involving anything supernatural:
1. I can assume that the nature of Maya visiting pre-accident and the nature of Maya encountering post-accident being different. For example, the playdate took place due to a normal visit between the families, then Maya showed up to Akira's tutoring castle a few years later due to her running away from her family.
2. Or, the first playdate was also a result of a runaway attempt; Arakawa family found her, let Ami keep her company for a little while without telling Ami what happened, before locating the Makinami family and sending Maya back.
3. [Be creative here]
I will acknowledge that I have
zero proof to support anything above and all of it is essentially creative writing. But, I will say that the mysterious playdate girl being Maya is, for the time being, the "least unlikely" option. This is because, compared to Maya, the past of other main cast girls are a lot clearer, leaving considerably smaller wiggle room to insert any hypothesized scenario that can make sense of this playdate without clashing into preestablished knowledge about the said girls (Simply put, in my eye Maya as a candidate will survive the most rounds of process of elimination).
Like the case of Rin and Sana you brought up; there would be so many "but if this is true, what about that?" type of follow up questions that will plummet their chances of being the playdate girl. Besides, I didn't think being a potential bastard of Nozomu was a required element that facilitated the said playdate (I understand that you're trying to find candidates with at least one additional layer of connection to the Arakawas). Thus, even if Nodoka's past is less clear and more suspicious than the aforementioned two, her chance is as big as the thread's favorite Otoha: low.
Maya on the other hand, her past history is highly connected to Akira, and is almost entirely unclear or well certified, and Maya herself has been shown to conceals information constantly even in the present days. Combining those with how other main cast girls (plus their moms if applicable) interact with Ami and Sensei in the current time, no other main cast girl has a suspicion level nearly as high as Maya.
You'd notice that I also assume that the playdate girl will exclusively turn out to be one of the main cast girls. Breaking this assumption is very easy and realistic, but narratively makes little sense. Because of that, this playdate girl's relevance to Sensei and Ami will also have to be high enough if such under the radar reunion is true. Noriko
might fit here under this lens, but I simply find dyeing a less than 7 year old girl's hair bizarre ever since her pink hair was proven to be natural (unless this in fact is a culturally common thing and I am massively unaware of it, or unless there in fact exists a possibly good enough reason for a preschool Noriko to dye her hair).
PS. I am not sure how valid the following can be, but I also assume that Sekai would know who this playdate girl is, and ghost Sekai has made comments on two prime candidates: Noriko and Nodoka. She doesn't seem to recognize neither (but yea asking a ghost mom to remember a girl from a playdate with your daughter well before she bit the dust might just be too much to ask)