Marian Slingeneyer

She is a Dvergr, also known as a dwarf, and is the first true member of GREMLIN introduced in the series, who is essential to their plans as she possess the skills to recreate legendary weapons of Norse mythology. Marian appears a seemingly swarthy skinned young girl. She wears overalls on her bare skin and seem not to wear any undergarments, here she holds several of her tools. Her silver hair is braided, her ears pierced with large circular earrings and she also wears glasses. She wears gloves, apparently for some sort of protection, being that she is magical smithee of some sort.

(Source: Toaru Majutsu no Index Wiki)