Guess what? I got really curious and wondered if there were Japanese Christian bands and I found a great band called Imari Tones! They're a Japanese Christian Metal band and they are sooooooooo good! I highly recommend them for anyone 'cause I already love 'em! Here's one of their songs, it's called "Faith Rider" and it's my current fave of theirs lolz. Hope you guys love them as much as I do!
http://www.youtube.com/watch?v=PnJfDEbhm1s