The name tag is kind of a mystery to me. When I put the characters into a translation program, it either comes back with things that don't make sense, or it can't find a translation. Phonetically it reads like "tag me", but is written in hiragana instead of katakana that would be expected for an English phrase.

The name tag says "Tatsugami" (although the つ looks small), she's probably Touma's little sister Tatsugami Otohime. She was Misaka Mikoto in appearance due to Angel Fall.