Episode 52

The Mu in Muichiro (無一郎の無) is the 52st episode of the Kimetsu no Yaiba TV anime series, and the 8th episode of its third season.

Synopsis
After falling out of the water pot, Muichiro begins the task of removing the needles stuck into him, but he quickly feels the numbness in his body caused by the needles’ poison. After removing them all, he notices the unconscious Kotetsu and the bladed fish demon about to attack him, seeing more demons join the first. Losing strength and unable to stand, he sees the demonic spawn pounce on the young smith and his life flashes before his eyes; he sees his father encouraging him to get up.

A young Muichiro struggles to stand with his load of lumber but finds the strength to rise up and run to his father. Owing to his work as a lumberjack, he would help his father cut down trees and enjoyed doing it, seeing the smile on his face as he worked. One night, as a storm raged, his sick mother’s condition begins to worsen. Muichiro tries to tell her that their father had gone out to pick medicinal herbs; feeling her high fever, he changes her wet rag and puts on another futon as comfort. She only mutters, “It’s cold”, leading Muichiro to hug her and state that his father will come soon. Outside in the severe weather, Muichiro’s father reaches a cliff face and sees the herbs.

He struggles to reach for them, stretching his arm to take a bundle for his wife. As he inches ever closer, the rock he is standing on suddenly breaks and he falls to his death, clutching the herbs in his hand. His mother would succumb that same night. Without his parents at the age of ten, Muichiro believed he was alone, only to recall that it was when he was eleven that he was alone; he in fact had a twin brother named Yuichiro at that time. As the two walked back home from their parents’ graves, Yuichiro began to speak of his disdain towards compassion, believing that helping others is meaningless. Muichiro, hurt by his twin’s hostile remarks, speaks up and said that helping others will help themselves.

Hearing this, Yuichiro tells him not to believe the words of a dead man who failed to save someone. Muichiro chides him for speaking ill about their father but Yuichiro states that the herbs could have never heal their mother, remarking that if he had not gone out, they would have only one dead parent. Muichiro is shocked by Yuichiro’s harsh statement but his twin bitterly spits back that he is telling the truth, ordering him to be quiet. Yuichiro tells him the Mu in Muichiro is taken from the word for incompetence, muttering that their conversation is pointless. He adds that the Mu in his name also comes from meaningless, causing his twin to cry.

Muichiro recalls that he would act like his twin whenever he lost his memories. He remembers that living with Yuichiro was stifling and he believed that his twin was a cold individual who hated him. Two seasons later, during spring, Muichiro went to fetch water by the river. Upon telling Yuichiro, he only expressed annoyance in him not doing so beforehand. At the river, he was happened upon by a white-hair woman, Amane Ubuyashiki, expressing surprise at her beauty and initially believing she was a forest spirit.

After she introduced herself as the wife of the Demon Slayer Corps’ leader, Amane stated that she had come to the mountains to give an offer. However, a hostile Yuichiro turn her away and forced her to leave. That night, Muichiro expressed to his twin his excitement when Amane had told them they were descendants of the swordsmen who used the first Breathing Style. Yuichiro ignores his glee and orders him to help out with their dinner. Muichiro tries to tell him that they should become swordsmen after learning about demons, believing they could help people.

Listening to his twin’s optimism and belief they can help others, Yuichiro slams his knife down onto his cutting board, silencing Muichiro. Seething with anger, he furiously asks how Muichiro could even believe he can be a swordsman when he cannot even cook rice. Stating he is exactly like their father and mother, he insults Muichiro’s continual optimism, remarking how their mother had continued working and kept her condition hidden from them and mentioning how their father had went out to get herbs in the middle of a storm. Angrily recalling how he had told their mother to rest and how he tried to get their father to stay home, he bitterly declares that helping others is reserved for the chosen few.

Questioning what could they possibly do despite being the descendants of swordsmen, Yuichiro asks Muichiro if he truly believes they can become swordsmen, answering himself by stating that all they can do is die a pointless death because they have no value, just like their parents. He claims that Amane will use them for different reasons and flatly declares the conversation finished, before ordering him to help make dinner. As Muichiro tears up from his twin’s verbal lashing, he recalls that they have never spoken to each other since that day, with the exception of the day they had fought when Yuichiro had splashed Amane when she visited them again.

Since Yuichiro’s outburst, he had continually ignored Muichiro even when he needed help, always having a scowl painted on his face. When a particularly hot summer came, both twins found themselves even more irritable; even the nights became hot and attempting to sleep became difficult with the heat and buzzing cicadas. One night, Muichiro moved about on his bed unable to sleep, sweat covering his body. He got up to take a drink and saw that Yuichiro too was awake, bothered and sweaty as well. Without warning, a demon appeared in their home, who expressed surprise that only children was at home, before turning to Muichiro.

Yuichiro leapt out of bed to stand in front of him, only for the demon to slash at him and sever his left arm, spraying the twins in blood. Muichiro quickly grabbed his agonized twin and moved him to the corner of the house as the demon became annoyed at Yuichiro’s screaming. The demon tells them that poor lumberjacks are useless anyway and said that them being alive or dead didn’t matter, stating that their lives were pointless.

Muichiro, upon hearing the demon’s insults, suddenly lost himself in an incredibly violent rage that he had never experienced before, remarking how even recalling it now, he could not believe it happened and stating that he could not remember anything when it happened. One moment, Muichiro saw himself screaming a vicious roar from his throat and in the next, he saw the demon brutally butchered with several gardening tools and pinned with wooden stakes and stones. The demon, despite his wounds, continued to twitch in agony as he could not die. Shortly after, sunlight shone on his body, causing him to finally burn into ash and perish.

After watching it die, Muichiro dropped his weapons and walked back home, only to collapse just a short walk away from the front door. Desperately wanting to reach Yuichiro, Muichiro struggled to crawl the remaining distance. After finally making it home, he saw his twin was barely clinging to life and made his way to him. He saw that Yuichiro was praying to the gods to save his brother because, “''He’s not like me. He’s a kind-hearted kid. He wants to help people… but I stopped him”''. Denouncing himself as the only one to blame, he prays for only himself to be punished instead and he finally recalls where the Mu in Muichiro’s name came from, as his twin began to cry and hold his bloodied hand.

Recalling Yuichiro’s last words that the Mu in Muichiro comes from “infinity”, Muichiro rises up; his faces become marked with two red cloud-like patterns as he grabs his blade and uses Mist Breathing, Fourth Form: Shifting Flow Slash, grabbing Kotetsu and eviscerating the fish demons instantly. Checking on Kotetsu, the young swordsmith tells him to not pay him heed and instead move to help Hotaru and protect the Sengoku period sword, to which the Hashira obliges. Gyokko, now entirely livid, watches as Hotaru continues to polish his blade and ignore him, despite now sustaining numerous slashes throughout his body and a lost eye. Notices the heavily injured Kozo nearby, he decides that killing him should finally get a reaction out of Hotaru.