How do I unlock Mirai and the others?

Hi guys I just got the game today (as writing this post) and I'm enjoying it even if I have no idea where I'm going or what I'm doing in the menus, but I'm at odds ends at how to unlock Mirai and the others because I really wanted to play as Mirai as shes my favorite character for various reasons, but I was a tad upset to find out that I couldn't play her right away.

I've looked around this forum quite a bit before posting this and found nothing and I tried to Google this as well but couldn't find anything.

Could anyone help me please?