[quote=Tatsua Aiisen]Yes, their appearances are totally far off. Unless Tyren was blessed with an abnormally large and strong body, that is. And unless Kei had the body of a fully grown woman at 15 (which is admittedly more likely.)

Yes, but their bodies aren't physically mature (and neither are their brains.) That means that, even if they trained their bodies or grew mentally, there's only so far they could go. The different would be noticeable, but not significant. To begin with, their physical bodies probably wouldn't be trained, since it's magical power that matters most, not strength.[/quote]

Tyrien is large? He isn't a twig at all but rather fairly built, but big? I've seen Grade 9 football players more buff than him.
+I never gave any suggestion to his physical strength in the CS.

I really don't much that's too physically mature on either. Tyren's just a bit fit after years in the field, Kotomo honestly could have just gotten an earlier growth spirt
You even agreed that it's likely in her case. As for brain maturity, I meant in terms of life experience. I know they're physical brain isn't still building but they still have experiences. 
Ever see cases of people who are rather young but matured really fast because they were put in a tough environment? Put most of them under a brain scan and their brains would probably still be physically growing/developing. But their experiences gave them insight/maturity unusual for their age, and constantly fighting and seeing friends die and turn into witches is sure as hell one way to do that.

And yes, magic is helping a lot. But they are still running around, jumping, moving and swinging their weapons a lot. It would still act as a form of exercise, especially sense a lot of the magic is probably invested in the flying and magical attacks. Actually it would also make since for them to try to keep themselves fit, so they can focus more of their magic on their spells rather than keeping the body from giving out and damaging itself (which, although heals fast and has a lack of pain due to the soul gems. It's still bad to have a damaged/stressed body in the middle of a fight).