Mu Dan had short red, plant-like hair, golden colored eyes with thick eyelashes, and kept a constant smile on his face. He had a well-toned build and wore a traditional Chinese robe associated with Taoism and a beaded necklace with a flower attached at the end.
During his first appearance, Mu Dan's head was not completely formed, and the top part was covered in flowers.
In his Kishikai form, Mu Dan had a pair of bodies representing his Yin and Yang form, that were locked together from the head. The bodies had long, elongate necks and one thin, long arm. The bodies were attached to a large, bloomed flower and were being supported by two legs that split from the bottom forming two thin sticks.
Mu Dan had a cheerful, yet sadistic attitude. He was very blunt with his words, telling Hōko that his religion was a lie and Sagiri's group that the Elixir of Life doesn’t exist. As stated by Rien, Mu Dan enjoyed toying with humans that came to the island. He thought nothing of them but as merely research material for his obsession of modifications and turning them into Tan. Once modified, Mu Dan views them as his “toys” that he can do whatever he commands them to do.
Although he had a low opinion on humans, he was able to distinguish ones that showed promise and became interested in them, such as Yuzuriha, Sagiri, and Shion. When he sensed that Yuzuriha was able to perceive Tao, Mu Dan's curiosity opened up as to how far she can go if she was able to wield it properly by teaching her. However, this could have be seen as being beneficial for him in some ways, as he stated that if Yuzuriha displayed the talent in wielding Tao, he would engage in Bochu Jutsu with her in order to strengthen his abilities.
After transforming into his Kishikai form, Mu Dan lost control of himself and became insane, which was expressed by his manical laughter.
He seemed to get along quite well enough with the other Tensens, shown as they were all having a nice conversation. However, he showed no signs of pity for Zhu Jin's weakened state. Mu Dan stated that he was a believer in functional beauty and preferred the male gender because there was nothing wasted in its composition.
Over 1,000 years ago, Mu Dan and the other Tensen were created from the Tao of Xu Fu and Tao from plant. The Tensens then trained themselves in the ways of Tao and turned the humans that came to the island into Tan.
Lord Tensen Arc
While having a meeting with his fellow Lord Tensen, Mu Dan gives his opinion of the male gender and ridicules Zhu Jin's weakened state. After Rien arrives, the group discuss matters regarding the humans that made landfall. They then finish off with a toast to their longevity and to Soshi.
He later engages in Bochu Jutsu with Tao Fa and discusses the possibilities of one of the humans escaping from the pit.
After Sagiri, Senta, Yuzuriha, and Hōko reach the Hōrai gate, Mu Dan stands waiting for their entrance. Once they entered, Mu Dan cuts Hōko's head from a distance and becomes impressed by how they made it this far. Yuzuriha attempts run away, after sensing how dangerous he was, but Mu Dan instantly catches up and restrains her. Sagiri points her sword at him to demand that he let her go and introduce himself. Still alive, Hōko introduces him based on his epithet, but after hearing this and his belief that his soul will rest in Hōrai, Mu Dan bluntly tells Hōko that the religious believes were all lies in order to maintain order on the island. He also tells them of the Kyoshi, human modifications that he had made to the humans that had drifted on the island. After he spoke of also turning humans into Tan, Senta questions if he was speaking about the Elixir of Life, which confused Mu Dan as to what he was talking about. Figuring out what he was referring to, Mu Dan tells them that the Elixir of Life does not exist since it will not benefit humans. He then tells them to surrender but is caught off guard after Yuzuriha substitutes her body with an Arborified tree and attacks Mu Dan. Mu Dan survives after regenerating and becomes impressed with Yuzuriha's skills. He then commands his Kyoshi to attack her and explode. However, she survives the detonation which causes Mu Dan to notice that she can perceive Tao. Becoming impressed with her potential, Mu Dan declares that he will teach her how to wield Tao through their battle.
Not interested in fighting the two, Mu Dan leaps towards Sagiri and attacks her from a distance. He then explains to Yuzuriha how he managed to accomplish this feat and says that he will start by teaching her the core fundamentals. However, Senta interferes and cuts both Mu Dan's hands and right foot. This gives Yuzuriha an opportunity to attack with her ninjutsu, but Mu Dan quickly regenerates from her attacks and comments that her technique needs improvement. Senta cuts the top of his head, figuring that without his sight they may stand a chance. After hearing this, Mu Dan proves them wrong by not regenerating his eyes and dodges every one of their attacks, explaining that Tao allows him to feel out their intent. He then takes note of Yuzuriha's previous technique early, saying that she possesses the same attribute he does and how she was close to achieving hōjutsu. Mu Dan avoids a sneak attack from Sagiri and says that she is powerless against him. Knowing that he can predict her attacks, Sagiri throws her sword towards Mu Dan's stomach and cuts his lower half, using the advice Hōko provided about cutting his tanden. However, Mu Dan survives Sagiri's attack due to not using Tao against him. Having gotten close to him to confirm her suspicion, Sagiri unleashes a burst of Tao. Mu Dan reads her next attack and jumps back, but has his face slightly cut. Mu Dan realizes that Sagiri can also use Tao but sees that their is more to it and smiles in delight.
Mu Dan smiles in satisfaction after learning that Sagiri possesses Tao that is toxic to him and wonders which one of them will come out on top. He seemingly vanishes from their line of sight and tries to attack Sagiri first. However, he is restrained by Yuzuriha's mucus strings, giving Sagiri the chance to attack. Mu Dan counterattacks by emitting a blast of Tao from his mouth and commands the Kyoshi to attack Yuzuriha. After Senta protects her, Mu Dan frees ones of his hands and attacks Yuzuriha with a Tao projectile. She sees the attack coming and jumps out of the way to have Senta take the hit. Mu Dan then dodges Sagiri's sword strikes but has his feet cut by Yuzuriha and Senta. He then takes a lot of damage by their combined attacks, but shortly moves out of the way by having himself float in the air. Mu Dan transforms into his Yin form and controls the Tao in the air to form large spheres. He then has them rain down to destroy the whole area. Yuzuriha tries to restrain his leg but Mu Dan sends his attacks towards her way. However, Mu Dan is pulled down by Yuzuriha still conscious. He is then stabbed by Senta from behind, giving Sagiri the chance to completely slice through his tanden, killing Mu Dan.
Shortly after, Mu Dan's corpse starts to bloom and sends a stinger towards Yuzuriha but instead stings Senta. Mu Dan then transforms into his Kishikai form and attacks Sagiri and Yuzuriha. However, Yamada Asaemon Shion arrives in time to cut the stingers and prepares to fight the monstrous Mu Dan. Mu Dan faces off against Shion and manages to leave scratches on his body using his stingers, causing him to sprout flowers. Mu Dan notices that Shion possesses Tao that can harm him and release more stingers. He then fights against Sagiri and Nurugai who act as decoys to have Shion kill Mu Dan. After having all his stingers cut by Sagiri, he sees Shion about to attack and kicks him backwards. However, he plants himself on the ground and quickly rushes in to slash away at his feet, immobilizes Mu Dan. Shion pushes through while Sagiri restrains one of his hands with her sword. Shion manages to get behind Mu Dan and attacks his two tandens with a Tao-enhanced sword strike.
As Shion swings his sword down, Mu Dan senses that he has stopped his blade after not sensing any strong amounts of Tao coming from his tandens. He then regenerates his stingers and attacks Shion, however, he dodges after Shion is warned that Mu Dan's weakness is his ovule located at the center of his flower. Shion cuts the ovule and sees a gathering of Mu Dan's heads. One of Mu Dan's heads becomes captivated seeing Shion facing death and wishes that he could tell Rien of this scene. After Shion brings his sword down, Mu Dan happily thanks Shion for making him experience death. His death then causes the surrounding area to bloom flowers.
Abilities and Powers
As one of the rulers of Kotaku, Mu Dan had partial authority over everything that went on and could command the Dōshi, Mōnshin, and Sōshin. His very presence was enough to scar Yuzuriha, a very formidable kunoichi that was marked for death, into quickly running away.
Mu Dan had enough strength to crush stone with his bare hands. He showed incredible speed, being able to catch Yuzuriha in an instant without having Sagiri and Senta notice him after bypassing them. He was also a skilled hand-to-hand fighter, capable of taking on the combined efforts of Yuzuriha, Senta, and Sagiri with little effort.
- Further information: Tao
Mu Dan possessed Earth-attributed Tao and had complete mastery over it. He could accurately sense the movements of his opponents and avoid sudden attacks effortlessly, demonstrated when he dodged both Yuzuriha and Senta's attacks simultaneously without the use of his eyes and avoided a sneak attack from Sagiri. Mu Dan could also emit his Tao from a distance to cause damage to his opponents from within.
Mu Dan could use senjutsu, to opt for more stronger Tao attacks. Through it, he could expel Tao from his mouth, instead of with his hands, and bombard his opponents with large, boulder-shape water droplets created from the Tao in the air.
Mu Dan could also use hōjutsu to either conceal his presence, as a way to sneak up and attack his opponents, or control the Tao in the air to give him flight.
- Distant Strike (遠当 Tōate?): Mu Dan launches his Tao from a distance as invisible projectiles and is strong enough to cause major damage from within the targets body.
- Hōjutsu: Earth Yin — Night Pilgrimage (方術 己の位 夜詣 Hōjutsu: Tsuchinoto — Yakei?): Mu Dan uses his Tao to conceal his presence from his opponents line of sight and sneaks up to make a surprise attack. This is called Hojutsu: Earth Yin Night Pilgrim in the Viz Manga.
- Hōjutsu: Earth Yang — Sky Pilgrimage (方術 戊の位 空詣 Hōjutsu: Tsuchinoe — Kukei?): By controlling the Tao in the air, Mu Dan is able to levitate. This is called Hojutsu: Earth Yang Sky Pilgrim in the Viz Manga.
- Senjutsu: Stabbing Tin (仙術 錫刺 Senjutsu: Suzusashi?): Mu Dan creates boulder size Tao orbs and have them rain down on his opponents to cause massive damage. This is called Senjutsu: Tin Splinter in the Viz Manga.
Mu Dan was able to regenerate any injuries he might take, including fatal ones that could normally kill a human being. After having his upper body shredded by Yuzuriha's ninjutsu, Mu Dan was able to completely heal himself in mere seconds. He could also stop his regeneration on certain parts of his body if he wishes. Mu Dan's regeneration can only be nullified for a short amount of time if he faces an opponent that possesses the Wood-attribute of Tao and the only known way of killing him is if the said Wood-attribute user completely destroys his tanden, which acts as his source of power.
Mu Dan was able to switch chi's of either Yin or Yang to augment his Tao and recover any lost. As Mu Dan switched in and out, their sex changed to match the chi, which was put to use whenever they engaged in Bōchū Jutsu training.
With what little consciousness he had after having his tanden destroyed by Sagiri, Mu Dan transformed into his Kishikai form. In this monstrous transformation, Mu Dan was able to produce multiple vines with flower-shaped stingers that when stung, or given the smallest scratch, caused his target to hallucinate and sprout flowers from their body. He was also able to shoot multiple laser beams that caused a lot of destruction.
Mu Dan was a very intellectual scientist, having created the Kyoshi from modifications of the past humans that have ventured the island. The Kyoshi followed the orders of what Mu Dan order them to do and could denotate to secrete a corrosive liquid.
- Like the rest of Lord Tensen, Mu Dan is named after a flower. "Mu Dan" (牡丹?) meaning "peony".
- Mu Dan ranked 29th place in the manga 1st Character Popularity Poll.