Profession: Vagabond, and former Pirate
Weapons: Double-edged katana and Tanto
Fighting Style: mix of various styles incorporating rapid, irregular movements he dubs "Champuru Kendo"
Quote: "I don't give a rat's ass about going to hell. I guess it's because I feel like I'm already there!"
Mugen was born in a penal colony on the Ryukyu Islands, which in the Edo period was a separate kingdom with close ties to the Satsuma domain of Japan. Rude, lewd, vulgar, and nihilistic, Mugen relishes being a pain whenever he can. His name means without limitation, as the components of it are the characters for "without" and "limitation." Incidentally, he writes his name using the Infinity symbol, a pun on his name, 'Mugen' is a homophone of the Japanese word for 'eternity'. The exact date of his birth is unknown. Some speculate that he is something of a throwback to Spike Spiegel's persona during the time previous to his falling out with his comrade Vicious.
He carries two blades, one a small tanto concealed at the end of his scabbard. His more principal weapon is a unique sword sheathed across his back—possibly a shamshir. His clothing is anachronistic as well, reminiscent of baggy hip-hop fashions of today. His gi functions more like a jacket and his hakama is cut off at shorts-length, resembling loose-fitting Bermuda shorts. His black hair is unkept and similar to an afro or Spike Spiegel's, being one of a number of similarities he shares with Spike.
Highly unorthodox swordplay and capoeira-esque movements make him a force to be reckoned with. His fighting style is probably best described by Kariya Kagetoki when they fight in Episode 25: "Interesting. You utilize erratic movements to prevent your enemies from predicting your next move." This is further evident in that his moves become increasingly erratic and unique as his opponents are more powerful. Mugen also has a tendency to parry attacks with the steel base of his geta.
He and Jin fight from time to time, but there is an undercurrent of mutual understanding between the two. Mugen's Japanese is quite rough and "Yanki"; he is illiterate until later in the show. The blue tattoos on his wrists and ankles indicate that he was once in prison. The circumstances of his imprisonment, and whether he escaped or emigrated legally, are unclear at first. It is later verified that he was to be executed for engaging in piracy. He was presumed dead when he plunged into the ocean, but survived.
Mugen seems to be the character most enshrouded in uncanny elements. For starters, he seemingly learned Hakkei in order to defeat Shouryuu, though he is never seen using it after that. Furthermore, he seems to be incapable of dying, or at the very least has a body that is more resistant to life-threatening injuries than the average person. When on the verge of death, he appears to cross into a mystical world in the Ryukyuan religion called Nirai Kanai—depicted in Samurai Champloo as an upside-down mirror world—overseen by the Futuchi who are dressed in black-feathered robes and carry spears. With each visit to this world he is subsequently 'rejected' after protesting that "I'm not ready to go yet." He has been brought back to life in this manner on at least three occasions. It has been speculated that his survival is because he is being preserved for a greater purpose, possibly his saving Japan from American conquest in "Baseball Blues".
Coincidentially, his seiyu, Kazuya Nakai, is also known for playing the "Pirate Hunter" Roronoa Zoro, in the popular shonen anime One Piece.