Genetically-engineered soldier who has a very close attachment to Meg and works under Sei.
A teenager who seems to have a spotty memory of her past. Jo is a very skilled gun[wo]man with silver hair, red eyes, and a strange glowing tattoo that stretches along her left arm and shoulder that appears during dramatic fight scenes. She often carries a pair of Desert Eagles with her and pants that don't contain a middle. Often maintains a stoic composure and spends much of her off time watching horror movies. However, if anyone tries to hurt or kidnapMeg (a surprisingly frequent occurrence in this series), she will hunt them down no matter the consequences.
Later in the series, it is revealed that Jo was a genetically-engineered warrior, bred for combat and little else by the mysterious RAPT organization. She also has a rivalry with a young soldier from the same program named Maria, who frees her from RAPT for the sole purpose of finishing the battle they fought with each other many years ago.