So we know:
1 – his family is very old-fashioned;
2 – they live in the mountains;
3 – they shoot messages on arrows and he can catch those arrows;
4 – he moves really fast;
5 – most people find him inscrutable;
6 – when he wants to be, he can be intimidating, but people don’t know why he intimidates them.
I’m thinking he’s got to be a ninja.
But he doesn’t have the mark of the ninja.
That makes sense, because a good ninja wouldn’t want to be identified as a ninja most of the time.