Mugen (無限, Infinity) is one of the main male protagonists of Samurai Champloo along with Jin. Both Mugen and Jin accompany Fuu in her search for "the samurai who smells of sunflowers." Mugen serves as a foil to Jin in terms of personality and disposition. His fighting style is characterized as being reckless and erratic.
During the title cards, his totem is the rooster.
Mugen has messy black hair and a faint beard. His clothing is anachronistic as well, reminiscent of baggy hip-hop fashions of today. His attire consists of a light grey shirt with a stitch pattern running down the middle and ending at the halfway point of the shirt. He wears this under a red short-sleeve happi that functions as a jacket. He wears dark gray hakama cut off at shorts-length, resembling loose-fitting Bermuda shorts and Japanese Geta (wooden sandals) on his feet. these geta are fitted with several metal strips on the soles, allowing him to use his sandals as blocking devices. He has two blue ring tattoos, two on each wrist and two just above the ankles. Lastly, he carries his sword on his back with a sash that goes from his left shoulder to his right hip, favoring his right hand. It has a zig-zag pattern of green and yellowish-brown.
Rude, lewd, vulgar, conceited, temperamental, and unhinged - Mugen is something of an antihero. He is fond of fighting and has a tendency to pick fights for petty reasons. In several episodes it is made clear that Mugen is a womanizer, and his libido often gets the better of him. Character designer Kazuto Nakazawa stated in an interview: "When I was doing character design, the most difficult one was Mugen, as I expected. I'm pretty sure that as far as the director's image went, he probably was thinking of someone like a 'rapper who acts like a bad guy.' But the way Mugen acts is relatively based on his core conviction."
Mugen is extremely competitive, and will take on any and all challengers. On top of his consistent rivalry with Jin, he is prone to gambling and taking on fights with anyone else he deems strong enough. He is also a sore loser and will go to great lengths to redeem himself from a defeat.
Mugen absolutely despises authority of any kind. His anarchic behavior stems from his childhood growing up in the lawless and often violent Ryukyu Islands. Mugen states he would rather die fighting than be on his knees pleading for mercy. His disdain for authority is so great, it even led him to attempt suicide by jumping off a cliff and into the ocean as opposed to being apprehended.
In spite of his faults, Mugen is capable of accepting people as comrades, if begrudgingly. If Mugen sees a skilled opponent, he will hold a high degree of respect to them (like Shoryu, Ishimatsu, Sara, Okuru, Kariya Kagetoki, and most importantly Jin). Originally Jin and Mugen did not get along well, but over time Mugen grew to respect Jin and even consider him as a friend. Jin killed Mukuro because he thought Mukuro stole his kill, and Mugen tried killing Sara because the only person Mugen considers worthy to kill Jin is himself. At the end, Mugen admits he doesn't want to kill Jin. Mugen also respects Fuu more than Koza (even though Koza likes him) because Fuu is more independent.
Mugen was born in a penal colony on the Ryukyu Islands (most likely Miyako Island since it was a penal colony in the past), which in the Edo period was a separate kingdom with close ties to the Satsuma domain of Japan. During his childhood, Mugen had to resort to piracy and committed several crimes with Mukuro and his stepsister Koza. One day Mugen is captured by government officials and sent to be executed over a cliff. Mugen jumped off the cliff to escape the officials, with Mukuro and Koza watching.
Mugen would later wander around, before going to a restaurant where Fuu worked at in the pilot episode Tempestuous Temperaments. He notices Fuu is dealing with rude customers, and offers her his services in exchange of 50 dumplings. Fuu declines by saying 20 dumplings, but accidentally spills tea on the governor's son. The governor's son holds Fuu down and plans to cut her to pieces, but when Fuu yells "100 Dumplings!" it motivates him to take on the rude customers.
The governor's son tries to reason with Mugen by bragging about his lineage, but Mugen doesn't care since he was rude to people and breaks his fingers while telling the governor's henchmen to bring the best bodyguard. Just then, Jin appears, and Mugen assumes Jin is the bodyguard, and they both fight for an even amount of time. During the battle, a man name Ryujiro burns the restaurant down, framing Mugen and Jin while also killing the governor's son.
The governor orders Mugen and Jin to be executed but Fuu manages to help them escape by throwing fireworks at the officials. Fuu, Mugen and Jin meet up, and Fuu manages to meet up with Mugen and Jin who are about to rekindle their fight from earlier, but she tries to stop them since she still needs the favor from them. She decides to settle it by flipping a coin, which Mugen decides to flip for her. It comes up heads, meaning they don't need to escort Fuu, but Fuu lies and says its tails before being chased by government officials.
Mugen, Jin, and Fuu would meet Ryujiro again, and kill him alongside with Inuyama and Oniwakamaru. Mugen, Jin and Fuu would go on to have many adventures together. Often times they split up due to being annoyed with Fuu, but would come back to help Fuu in the end. The first example is Mugen and Jin ditching Fuu, but would come back to take on Nagamitsu and his Yakuza gang. Mugen would also meet many skilled foes whom Mugen has respect to, like Shoryu, Ishimatsu, Okuru and Sara.
In Misguided Miscreants (Part 1) and Misguided Miscreants (Part 2), Mugen, Fuu and Jin would go back to his home islands where he reunites with Koza, Mukuro. Mugen isn't too pleased with seeing Mukuro due to his violent behavior, but agrees to raid a pirate ship. However, Mukuro sets the ships to explode to kill Mugen, while also deforming three officials that will fight Mugen in the future (Denkibou, Umanosuke and Toube). Mugen survives and kills Shiren while leaving Koza, Jin kills Mukuro (to avenge Mugen).
Mugen would meet Joji Titsingh, and help Jin rescue Shino from a brothel in Gamblers and Gallantry. During Beatbox Bandits (episode) Mugen accidentally gets high with criminals, and in Lethal Lunacy Mugen learns about ki to defeat Shoryu. In Lullabies of the Lost (Verse 1) and Lullabies of the Lost (Verse 2) Mugen and Jin would split up from Fuu, but come back to save her from Okuru and Yukimaru. Mugen would also meet a female ninja name Yatsuha Imano whom he become infatuated with.
In Unholy Union Mugen and Jin would help expose Xavier III for using Christians to create guns, and War of the Worlds Mugen would learn how to read thanks to Bundai. In Elegy of the Entrapment (Verse 1) and Elegy of the Entrapment (Verse 2) Mugen would meet Sara whom he saw as a mother. However, Mugen would try to fight against Sara due to him realizing that Sara "killed" Jin. In the first fight he is unsuccessful, but in the second fight he surprises Sara, however Sara nearly manages to kill him but stops, realizing that her son is already dead and willingly lets Mugen deal the death blow with Mugen throwing Sara's weapon in anger.
Mugen, Jin, and Fuu would eat mushrooms which cause them to hallucinate events in Cosmic Collisions, and play in a baseball game against American baseball players, with Mugen winning the match. In the three part series finale, after Fuu leaves them to face her father Seizo Kasumi, Mugen and Jin encounter Kariya Kagetoki, the Hand of God (Shogunate's right hand man).
Mugen tries fighting against Kariya, but loses due to Kariya's overwhelming skill and power. Kariya praises Mugen's unpredictable fighting style, but notes that Mugen's skills are limited as a result. Kariya fights against Jin with Mugen trying to help but Kariya brushes him aside. Denkibou arrives and tells Mugen that his brother Umanosuke and Toube capture Fuu on the island. Mugen tells Jin to defeat Kariya while he rescues Fuu.
During the boat trip, Mugen kills Denkibou and faces off against Umanosuke and Toube after he frees Fuu. Mugen gets tortured briefly before distracting Umanosuke and getting his sword back. Mugen ultimately kills Umanosuke by decapitating him with his own weapon before Toube blows himself up trying to kill Mugen. Mugen survives, and sees Jin. Fuu tells them to stop, but Mugen and Jin plan to finish their fight.
When their swords collide, it breaks. Mugen admits that he doesn't want to kill Jin anymore due to their adventures, with Jin agreeing as well. Mugen and Jin rest for a week before going their separate ways. Before they leave, Fuu reveals that she lied about the coin toss so the both of them could escort her, much to Mugen and Jin's surprise.
Mugen's highly unorthodox swordplay and a fighting style based on breakdancing - dubbed "champuru kendo" (Champloo Kendo in English) and ostensibly developed by himself - taking bits and pieces from all forms of martial arts and making up the rest on-the-go as he fights his opponents, make him generally unpredictable in a fight and a force to be reckoned with. He carries two blades: His principal weapon, a unique sword with a curved blade and a hilt with two prongs sheathed across his back, and the other a small tantō concealed at the end of his scabbard (only resorted to as a trump card). His main weapon appears to be an amalgamation of the Okinawan sai and Japanese katana. Mugen also has a tendency to parry attacks with the steel base of his geta.
Mugen's fighting style is unpredictable, which makes it harder for opponents to counter. Kariya Kagetoki praises this, however he notes that Mugen's skill level is lacking as a result. However, Mugen has a knack of learning things very quickly, once he sees his opponent doing a move he will try to incorporate it to his fighting style. Mugen is a prodigy at fighting, easily learning how to use ki to kill Shoryu and impressing Sara in his second fight.
- The name Mugen 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,' which is a homophone of the Japanese word for 'eternity'.
- Mugen's Japanese is quite rough and "Yanki."
- Mugen is revealed to be illiterate (due to him not being educated as a child). However, he learns how to read in War of the Worlds.
- The exact date of Mugen's birth and much of his past is shrouded in mystery.
- Mugen's style of clothes suggests he may be of Ainu origin. This appears to be further supported later on by Mugen remarking that he grew up on the same music an Ainu fugitive was playing (though the Ainu man came from the far North, and Mugen came from the far south). Another reason for the similarity may be because the Ainu of the north and the Ryukyu of the south are from the same cultural and genetic stock before being displaced later by the Yamato Japanese.
- In "Elegy of the Entrapment (Verse 1)", Mugen states that he never knew whom his parents were.
- The blue tattoos on Mugen's wrists and ankles indicate that he was once in prison where the circumstances of his imprisonment are unclear at first, but it is later revealed that he was to be executed for engaging in piracy.
- It is unknown if Mugen would return back to Yatsuha Imano whom she said she will marry Mugen when they cross paths again.