He has a variety of scars on his body, the most noticeable of which are a horizontal scar across his nose and a vertical one cutting through his left eye. His hair is usually tied in a ponytail.
Manji is shown to be laid back and shrewd with jaded and nihilistic tendencies.
Not much of background is known about Manji except that he once served under a local daimyo, enforcing his brutal rule (unknowingly) on the locals until he found out his lord was corrupt and killed him. For that he was hunted and was outlawed. He was later nicknamed "Killer of 100" after the amount of police officers that he killed.
The immortal samurai, Manji was introduced when he confessed his sins of killing a hundred men to a priest in a church. But in fact, the priest is actually Gyobutsu "Johnny", a bounty hunter in disguise. He then shot Manji in the head but Manji revived and cut off "Johnny"'s head instead. Later, Manji returned to an inn where he was staying with his sister and where a 800-year-old nun, Yaobikuni was waiting for him. It was revealed that Yaobikuni was the one who put the Kessen-chu (sacred bloodworms that allow anyone to survive nearly any injury and reattach severed limbs) in Manji's body. It was also revealed that Manji's sister, Machi that looks and acts like a child is actually a grown woman with a husband (which Manji killed). Manji was later shown in a flashback where he was chased by a group of police officers due to his act of killing a hundred men, including his lord. He crossed paths with Saito Tatsumasa and killed him in self-defense, without knowing that he's Machi's husband. After witnessing her husband's murder at the hands of her brother, Machi went insane and reverted to a child-like mindset. Back in the present, Yaobikuni offered Manji to give up his sword and travel with her as a monk but Manji refused.
That same night, Machi was kidnapped by a gang of ronins. When Manji rushed to rescue her, the head of the gang, Shido Hishiyasu wanted both his gang and him to fight one by one in exchange of freeing Machi. This is so that he can avenge his brother, Gyoubutso "Johnny". Manji, however offered to fight them all bare-handed but Shido refused thinking that he's insane. He then released Machi but killed her in front of Manji. Manji protected her body from being further sliced up by Shido but in the process, was stabbed in the back. Later, he killed Shido and all of his gang members to avenge Machi's death. He returned to the inn at dawn where he was still covered with blood. Manji then told Yaobikuni that he's not going to give up his sword and that he will kill one thousand evil men to pay his act of killing one hundred good men. Yaobikuni agreed and said that the Kessen-chu will leave his body after he killed one thousand evil men. Manji later collapsed in front of the inn, out of exhaustion.
Long afterwards in the story, Manji met Rin Asano, a 16-year-old girl who's the sole survivor of a massacre two years ago. Before that, Rin had been searching for him at the recommendation of Yaobikuni to hire an immortal and skilled bodyguard to aid her in her quest for vengeance on the man who lead the massacre that killed her parents, Anotsu Kagehisa. At first, Manji refused to help her but finally agreed because Rin looks a lot like his deceased sister, Machi. Later that same night, thanks to the poems that were sent by Kuroi Sabato (a member of Itto-ryu who was also one of the men who carried out the massacre) to Rin's family's dojo, both Rin and Manji found him beside a lake. From the flow of events, Manji's legs were chopped off by Kuroi and after Rin unleashed a secret technique on Kuroi which caused his shoulders and head exposed, a horrifying scene of two women's heads that is attached to both of his shoulders was revealed. One of the women whose head is attached to Kuroi's shoulder was Rin's mother. Out of fury, Rin unleashed the same technique but Kuroi evaded it. Kuroi then managed to convince her to kill herself but before she could do so, Manji managed to approach Kuroi from behind and stabbed him from the back. Afterwards, Kuroi was killed and both Rin's and Manji's quest for Anotsu Kagehisa's head continues.
This is a list of Manji's weapons that appeared in the manga but only those with names that are compiled in this list.
Shidō (四道; Literally "Four Paths"): Acquired from the samurai who killed his sister, this pair of short blades seem to be Manji's preferred weapon. The blade prongs off near the guard, allowing it to be used to catch other blades.
Imo-no-Kami Tatsumasa (妹守辰政; Literally Sister Defender Tatsumasa): This was originally the sword of Saitō Tatsumasa, the husband of Machi and Manji's former brother-in-law. It was forged by the famous swordsmith Toratoru Kotetsu. Manji often combines its with Kotengu by the hilt, just like how Saitō once combined it with another katana.
Kotengu (少天狗; Literally Little Devil):. A two bladed dagger. One blade forward, the other bending to the right. Manji seem to like climbing trees with this one. After Shidō and Imo-no-Kami Tatsumasa, this is the weapon Manji uses most.
Aun (阿吽; Literally Om) A two headed spear which can be folded up.
Sickles: Two sickles attached to each other by a chain that extends. Manji lent them to Giichi after Manji had broken his weapon.
Okorobi (男転; Literally Man Toppler):
Merabi (女蝱; Literally Lady Gadfly): Manji calls it an "ugly sword", one which is not meant for a sheath but to cause grievous wounds by ramming it into the flesh of an enemy and pulling it out again.
Immortality: Because of the Kessen-chu inhabiting his body, Manji has attained immortality. His body will always return to the state it was when the Kessen-chu were implanted, allowing him to sustain almost any wound. The only weaknesses of this immortality (according to Ayame Burando) are starvation, burning to ash, extreme cold, grievous damage to the bodily organs, lack of food or oxygen, being crushed to a pulp and drowning.
Swordsmanship Expert: Manji is an expert swordsman seeing as he was able to survive a hundred death matches before his immortality.
Weapon Master: Manji is a weapon master owing to the fact that he uses a large variety of weapons easily. It has been hinted that he's a collector.
Intelligence: Manji is very intelligent despite his looks. And shrewd.
Manji was a bodyguard and employee to Rin. They seem to have this brother and sister relationship but there are hints that may suggest a more romantic/intimate relationship. However, their relationship did not progress any further from their "siblings" status in the story.
Manji's equal from the aspects of physical strength and fighting skills. Although Magatsu was a former member of Itto-ryu, he joined forces with Manji to seek revenge on his lover's killer. Later, they became enemies again when he rejoined Itto-ryu.
In an incident where Rin and Shira teamed up in an attempt to defeat Anotsu in an ambush, Shira revealed his true colors when he killed three members of Itto-ryu (which Anotsu prepared to protect a prostitute that served as a distraction so he can travel to another dojo freely) and sliced up the prostitute. Rin, horrified by the scene, tried to stop him from killing the prostitute but it only angered Shira more. When Shira was about to kill Rin, Manji appeared and saved Rin by cutting off Shira's hand.
From then on, Shira swore to take vengeance on the man who took his hand.
- (About Machi) "I commit seppuku now, she dies in a ditch somewhere, all alone..."
- "Machi...this isn't a beancake. It's horse shit."
- "I've got something special for you - A taste of pain... such as most people could never even dream of!"
- "Sure, the memories hurt. But if you can hold onto them... sometimes they can make you as strong as steel."
- "There must be some reason of your own that you can't give up the sword! Remember that reason! Fight for it!"
- "Somehow for me... It's like I'm seeing it long ago and far away. I can't get into it. I guess there's no place for me in the normal world anymore."
- (To Rin) "If you want everyone to like you... then you can't even fart when you're out on the street."
- "Hyakurin, you devious bitch!"
- "I never thought you were this twisted. What do you fuckers think people are?!
- Manji is extremely similar to Himura Kenshin, Manji like Kenshin is seeking atonement for the people he killed in the past and they both are highly skilled ronins.
- Manji has the habit of naming new weapons after their owners.
- Manji likes to collect weapons and can hide them all easily inside his clothes despite their shapes, nature and size.