I'm glad the child won (or rather I'm glad she didn't get hurt), but this is fucked even by Japanese standards.
12 year-olds have no business being in a sport that involves strikes to the head, I don't care if she's some grappling prodigy or whatever. I know it happens in boxing, it's still wrong.
Apparently they used amateur-style protective head gear and shin guards, as well as larger gloves. Even with extra protective gear and a few rule changes, I feel like 16 should be the minimum age for amateur MMA. But Japan's gonna Japan...