While a colony of nanomachines, Emeralda has the appearance of a human child with copper skin, emerald colored hair and orange eyes, and a beige scarf covering her mouth and most of her upper body. At the time she was awake, Emeralda had the mental level of a 3 or 4 year old, resulting in her having a rather child and direct nature. Being different from others, this gives her a bit of a complex. She was created by Kim, Fei's previous reincarnation, often mistaking Fei for Kim.