Japanese Voice Actor: Kengo Kawanishi
English Voice Actor: Griffin Burns
Manga Debut: Chapter 44
Anime Debut: Episode 21
Muichiro and his twin brother, Yuichiro, have a woodcutter father and a mother who is a housewife. Their mother caught a cold that developed into bronchitis when they were 10. Their father went to look for medicinal herbs and was caught in the storm and died.
Soon after, the twins became orphans. Muichiro started looking after the two of them. The spring after they became orphans, they were visited by Amane Ubuyashiki and were invited to join the Corps.
Muichiro was excited to join the Corps but this was opposed by his brother. Yuichiro would even chase Amane away in the hope that she would stop inviting them to join the Corps. Yuichiro even blamed their parents for their deaths.
He said that they died because of their selfless nature and they should not be like that. One night, they were attacked by demons. Yuichiro lost his left arm while protecting his brother. Muichiro used all the tools he can find to fight the demon.
When the sun rises the demon turned to ash. When Muichiro returned to their house, his brother is almost dead. Yuichiro was praying that his brother would survive. Muichiro then lay beside his brother until he died. When Amane and his daughters arrive later, they nursed the wounds of Muichiro.
He then loses his memories of the past. He joined the Demon Slayer Corps and became a Hashira in only two months. Despite not having memories of his past, he has deep anger towards demons and has been his driving force while in the Corps.
Muichiro started having the cold personality of his brother when he was in the Corps. He is dreamy and just cannot be bothered. His extraordinary skills are arguably one of the best in the Demon Slayer Corps as Tengen would recall. In the Swordsmith Village, Muichiro would be seen arguing with Kotetsu.
When he was not given the key of Yoriichi Type Zero, he slapped Kotetsu. Tanjiro intervened and was surprised when Muichiro with a small frame and thin arms would not even budge.
Muichiro would be in a constant squabble with Tanjiro while staying in the Swordsmith Village. If he was not in a squabble with him, he would be using the mechanical doll, Yoriichi Type Zero to practice. After staying for a week in the village, they would face two of the upper-rank demons.
While he battles Hantengu and Gyokko, he starts to have a flash of memories. While in the middle of the fight, Muichiro’s blade broke. He was then handed a new blade by his new swordsmith, Kozo Kanamori.
It was during his battle with the Upper Moon 4 and Upper Moon 5 that Muichiro was able to awaken his Demon Slayer Mark. Muichiro along with Tanjiro and Mitsuri was able to defeat the upper-rank demons. Muichiro was poisoned but he checked on Kotetsu first before collapsing.
Tanjiro and Muichiro later thanked each other for what they did for each other during the battle. Muichiro also regains his lost memories. Mitsuri then pulls them together for a group hug. The next time they would meet will be during the Hashira training.
Before the training started, Muichiro was interviewed regarding what happened in the village. He was asked about the Upper Ranks and how he was doing. He later explained about the poison he got from Gyokko, how it rendered him immobile and he used breaths to slow down the effect.
He also explained how he got his mark and he thinks his body was 39 degrees Celcius when he got the mark. Later, Muichiro was given the task to train the other members of the Corps with their movement.
He will be training them with coordination techniques. When Tanjiro arrived on his training grounds, Muichiro became friendly with him and even complimented him. This is not something he had done with anybody. He calls the other members of the Corps useless and incapable.
The Hashira training was proven effective when the whole Demon Slayer Corps fought against Muzan and his minions. Muichiro was killed in battle against Kukoshibo.
The straight long hair that reaches to his waist compliments Muichiro’s pale complexion. He has a short stature and his hair is set loose on two clumps. These clumps would protrude slightly on both sides of his head. His mint green eyes are large and empty looking.
Muichiro looks the same as his twin brother Yuichiro. His Demon Slayer uniform is longer and has looser sleeves. The uniform is dark and slightly turquoise-tinted. His pants do not have bands around the calves. He wears dark blue tabi socks and a pair of white zori with white blue socks.
Muichiro is an airhead, impassive and selfish individual. Before his memory loss, he use to be warm and happy but he got the personality of his brother after he lost his memory. He is one of the most devoted members of the Corps. He does not care about people around him and he does not like talking or mingling with them.
He cares for the Oyakata and even flicked Tanjiro’s forehead for talking back to Kagaya. He has a violent side of him that he would gladly show to humans and demons alike. He looks down on people who do not have the same skill set as him.
Being able to rise to the rank of a Hashira for only two months after joining the Corps. He even easily overpowers the demon slayers who are older than him. His reflexes, speed, and endurance are some of the best in the Corps.
To be able to fight two upper ranks and hold them back at the same time only shows the kind of skill set he has. When he was fighting Kukoshibo, he was praised by him for his swordsmanship and fighting ability.
Muichiro was one of the first few who was able to awaken his Demon Slayer Mark. When he battled with Kukoshibo, he dyed his Nichirin Sword bright red and he was able to use transparent world. His endurance is extraordinary and this was shown when half of his body was already cut and he was still able to turn his sword bright red.
His willpower is one of the main reasons for his extraordinary strength. Losing his twin brother to the demon when they could barely fight back contributes to his rage.