Mugen has medium dark fur with black and white markings on his face and body. He has light pupils with black cornea.
Mugen and his minions were sent by Gaia to search for a dog who masters Zetsu Tenrō Battōga. While searching for information, they killed Bill and Bemu. They also cut off Hakurō's leg. Mugen has Noroi working for him. When Noroi became useless Mugen tried to kill him and left him believing that he was dead. Mugen then went into Reima's Palace with his fighters as their mission was to kill Reima. After Thunder Wolf and Mukonga had killed each other in battle, he faces the Hakkenshi Of Sirius who easily defeat his fighters. Mugen flees, revealing himself to be a coward, and is not seen again.