Is Mirai a peaceful person?
Can't simply define him that way
None of the above really fits
Who is 'Mirai'?
I used to think that yes, Mirai is very much a peaceful sort. He does seem to avoid using unnecessary violence, even though sometimes the provocation seems pretty severe. (What happened with the gossip reporter comes to mind.) But then Mebius kills monsters without barely a second thought. And there seems to be a few out of character (imho) instances of Mirai (and perhaps Mebius, too?) being more aggressive than usual (only the episode where that gossip reporter first appears does come to mind, though, so it's possible I'm making this stuff up). I don't know. Maybe it's more of Mirai using whatever means available (and not go too much (if it has to at all) against his moral code) to protect those he needs to protect.
As I said, I think too much and might make simple stuff more complicated...