Chris...Ayumu called her Yousei-san, but she's the most powerfull Masou Shoujo...don't want to spoil...
BUT HERE'S A GIANT SPOILER: VIEW ON YOUR OWN RISK:
I'm a Hardcore-Fan, so here's a pic from the Light Novel Vol 10 which will normally published tomorrow but I've already a pic~
DON'T LOOK AT IT: It's Seraphim's Masou Shoujo Transformation