A slim, fair skinned young woman with waist-length fair hair styled in a hime cut and light coloured eyes, Koko has white hair with light blue eyes and pale skin in the anime. When she was younger she maintained her hair at chin length and two years later has again cut it to that length. She is very similar in appearance to her brother Kasper, although they are not twins. Koko is usually well dressed, favouring business suits or similar attire, with or without neckties. She also wears a white coat with a feather-like collar. Because she has a tendency to burn when out in the sun, Koko usually wears a broad-brimmed straw hat when outdoors for an extended period of time.
Koko remains a largely enigmatic character, rarely revealing her true state of mind. She normally appears quite cheery and happy and sometimes acts immature when around her subordinates, having a tendency to throw fits when frustrated or angered. However she is able to rebound quickly and rarely allows herself to remain stuck. Even when in dangerous situations, she is able to keep a clear head and actually smiles when she is in danger. Previously she was unable to keep her composure when in danger but made a promise to Echo to do so after he was mortally wounded while protecting her from Hex and her unit and has since largely masked her true feelings.
She can be ruthless and determined, making her a very dangerous opponent as she will not hesitate to use various means, including deadly force, to achieve her objectives. However a single action or statement by an opponent can motivate her to display mercy towards them depending on the circumstances, and she has occasionally been willing to spare them. Koko is unafraid of weapons because she is in the business of selling them and believes that one should not fear one's merchandise. She has a fatalistic attitude towards her own death, feeling that if it is her time to go, then so be it but if not, then she will escaped unscathed.
For her business dealings, Koko only accepts payment in the form of cash although she once made an exception by accepting diamonds. She refuses to take any credit and has met attempts to pay her with drugs by having her squad immediately kill the payees. Because of the circumstances under which Echo was killed by Hex she has trouble sleeping when the moon is full, as she is reminded of the incident. Early on it was suggested that she has a tendency to sleepwalk but this was only shown once.