Okay, I've noticed some people seem to think I was planning this with Rain or something.

I wasn't, I wasn't even sure it was a good idea but it's the only place that's not very crowded for a new character to show up at.

Whatever I do with the NPC(still working on that) is going to be completely independent of if Rain decides to have Mokou show up anywhere in particular.

I'm fairly certain Rain's reasoning was that Mokou can't die so even if things go south in their interaction any violence would probably end comically rather then death, because... yeah Mokou can't die.