Jaken is Lord Sesshoumaru's faithful vassal. Jaken's been with Lord Sesshoumaru since the Great Dog Demon's death. He follows Lord Sesshoumaru where ever he goes and also has become a faithful companion to Rin, even though the young girl confuses him greatly. He carries Sesshoumaru's Staff of Two Heads.
Jaken know's much about the history of the feudal era, and often explains things to Rin that she normally would not understand. He teaches Rin medicinal herbs, and alot about Sesshoumaru. Although Jaken is a demon, he is very cowardly, and poses as the Shippo of Lord Sesshoumaru's group.