Gaikotsu is a member of the Mushikari.
Gaikotsu wear a mask that hides his face, he also wears a hood on his head. Under the mask he is hideously disfigured, apparently due to an incident concerning the Mushi. Gaikotsu also wear a black samurai kimono.
Gaikotsu is shown to be a dark person who will even willingly kill his own teammate if they fail and is happy to kill someone.
Gaikotsu apparently joined the Mushikari for revenge against the Mushi for destroying his body. He was apparently very handsome before this incident.
Gaikotsu was apparently disfigured by the Mushi at one point in his life, leading him to develop deep hatred for them.