Chain Sumeragi is the "Invisible Werewolf" and a member of the "Werewolf Bureau" that is assigned to Libra. While diligent in the field, she can sometimes come off as cruel or indifferent toward others, such as when she seemingly ignored Leo when he was being mugged, only to win his earning back later.

Despite this, she can also be quite sadistic, often causing physical harm to others, usually Zapp, with whom she doesn't get along.

As one of the werewolves, she is required to have a token that connects her to the material world in case she over-dilutes herself and her existence begins to fade. Her token happens to be Steven A. Starphase from Libra.