The sister of Mary Godwin, Shelly Godwin was, like her sister, held illegally by a pharmaceutical company to be used in drug experiments until their rescue by the Kukai Foundation. Unlike her sister, Shelly is all business, possessing a genius I.Q., and is able to perform complex tasks. She is often in the presence of Gaignun Kukai (Nigredo), helping him out.
A word of note: the names of the sisters, Mary and Shelly Godwin, is inspired by Mary Wollstonecraft Shelly, the author of "Frankenstein".
(source: Absolute Anime)