Will the story revolve around these 3 characters ? no BBC maybe ? no other dudes ?
So far the characters in the entire game that had appeared at least for 1 frame on screen in order of appearance:
1- Mio
2- Yamato, although only as first person view
3- Aiko, if you know you know...
4- Mahito, so far the most irrelevant character, but who knows What Viviny has prepared.
5- Ota
6- Akemi, or at least everything points in the direction that she's a different character and not Mio herself
7- Max_10i, who got rid of Akemi's wig.
So, I don't think it stays only on 3 chars for too long in the near future.