[Him]

I think it's the effort of research they put into each band. Because those girls didn't know what metal was. So my guess is they researched on Metal and then made their own spin to it. Which is the best way to make it yours. I don't think it would've worked if the sound was like any other metal band I've heard of. They have their own twist to it and I think that's one of the reasons why people like Baby Metal so much.