Mayumi Kirishima is an Enhanced, and a member of David's old paranormal investigation team.
While Mayumi cares very deeply for her companions, she is...outspoken, to put it mildly, and not shy of an opinion. Her interactions with Rainbow in the UA Sports Festival and Natsu in the Bobsleigh race in the Nature Universe show some shades of Erza in her personality, and for good reason...
It turns out that after the Enhanced Bomb went off, she became an Enhanced with the Requip Magic of Erza Scarlet and the Darkstalker Magic of Morrigan Aensland, the latter of which even gives her several demonic traits, including energy senses and brainwash immunity. However, because she wasn't much of a fighter before she gained these powers, she lacks the confidence to use them, and therefore, feels as though she hasn't fully awakened to them.
But all in all, it's those same powers that make her very versatile in a fight, and even displays mastery in piloting mechs. This girl is a scrapper in every sense of the word.