Episode 47

A Sword from Over 300 Years Ago (三百年以上前の刀) is the 47th episode of the Kimetsu no Yaiba TV anime series, and the 3rd episode of its third season.

Summary
As Tanjiro and Kotetsu sees that inside the battle doll is an ancient sword, they are joined by Hotaru Haganezuka, who insists on polishing it. He then meets with Genya, who is annoyed at his attempts at friendship and Muichiro, who is initially indifferent about helping others but sees something in Tanjiro. Unbeknownst to all, Gyokko and Hantengu have entered the village. The two are then confronted by Upper Rank Four, who, despite his fearful personality, hides a sinister and powerful secret.

Plot
After landing a blow on Yoriichi Type Zero, Tanjiro and Kotetsu watch as the head breaks away and reveals a 300-year-old sword in the doll. The two become ecstatic at finding such a weapon, with Kotetsu believing Tanjiro should wield it due to lacking his own. Tanjiro declines to take the blade but the smith notes that Sengoku period steel is noted to be the best quality, adding that Tanjiro being the one to reveal it has earned the right to use it. They eagerly unsheathe the blade but quickly become disappointed to see the sword severely rusted; Kotetsu apologizes for exciting Tanjiro, who meekly accepts with tears of disappointment in his eyes. Suddenly, loud footsteps shake the ground; they turn to see the now extremely muscular Hotaru Haganezuka approaching them and stating that the sword should be left up to him. Tanjiro and Kotetsu try to pull it away from the older swordsmith, confused by his statement and believing it should be Kotetsu’s, but Hotaru continues to insist on taking it.

Tanjiro mentions that he had been looking for him but the smith does not answer him, eventually pulling the blade away by shoving the two to the ground. Confused by the man’s immature antics, they are joined by Kozo Kanomori, who promptly demonstrates that by tickling his sides, Hotaru can be exhausted and calmed down for some time. With the eccentric swordsmith downed, Kozo talks to Tanjiro and explains that Hotaru had secluded himself in the mountains to train, in order to make a blade that would not break for him, surprising the Demon Slayer. He adds that Hotaru appreciates Tanjiro for believing in him to make a sword as other Demon Slayers dislike him, which Kotetsu chalks up to poor social skills. Hotaru then awakens and exuberantly declares that he will polish and restore the rusty blade, to which Kotetsu notes that he could have said so in the beginning, causing the muscular smith to angrily grab him; Tanjiro and Kozo quickly tickle him into exhaustion to save the boy. Before leaving, Hotaru provides Tanjiro with an alternate blade to use for the time being, for which the swordsman is thankful.

At the village the next day, Tanjiro speaks about Hotaru mentioning that the extensive polishing he will undertake is so intense, it has killed people; he grows worried for his safety and notes that even he is not allowed to watch. He relays his concerns to Genya sitting nearby, who does not care about his situation and demands he does not speak to him as a friend. Tanjiro is confused by his denial of friendship and Genya explains that it is because he had broken his arm at Final Selection, though the former states that it was due to him hitting a girl; he offers him a rice cracker, only to have Genya smash it.

While watching him speak, Tanjiro remembers that he was missing a tooth, which Genya vehemently denies; he pulls out the missing tooth as he had wanted to return it, disgusting Genya into kicking him out of the room. In his quarters, while braiding Nezuko’s hair in the style of Mitsuri’s, he muses on Genya’s constant anger and believes it is because he is hungry. While walking from the hot springs back home, a swordsmith finds an ornate vase on the steps. He reaches forward to grab it but is suddenly pulled in, squeezing and crushing his body through the opening until he is engulfed.

The vase then spits him out, his body horrifically mangled but the smith barely alive. Gyokko emerges and rants about his dislike for the taste of swordsmiths. Having infiltrated the Swordsmith Village, he hopes that destroying it will cripple the Demon Slayers. At a rooftop, Hantengu, having joined Upper Five in the village, remembers Muzan’s anger at the meeting and decides that killing everyone in the village will please him. In the forests, Genya enters the hut of his swordsmith; though he sees it is empty, he sees his completed Nichirin sword and looks intently at it, musing about his older brother and believing that “I have to do it”.

As Tanjiro sleeps, someone pinches his nose to wake him up and is revealed to be Muichiro, asking for the whereabouts of Kozo Kanamori, his new swordsmith. Tanjiro mentions that he may be with Hotaru and asks if he would like to go with him and search. Seeing the Demon Slayer smiling brightly, the Hashira asks him about why he cares so much about people, to which Tanjiro answers that helping people will always come around to help him and believes they can go together since the timing is fit.

His answer unexpectedly stuns Muichiro and he asks for what he had said earlier. Nezuko then awakens and cheerfully moves about as Tanjiro asks if he would like to go with him. Looking at the young demon, Muichiro remarks that she is odd but cannot explain why.

Suddenly, the two then hear someone outside their room. The door slides open and a tearful and anxious Hantengu begins to crawl toward them. Tanjiro and Muichiro are confused by his sudden presence but they quickly surmise that the demon is an Upper Rank. The Hashira unsheathes his blade and uses Mist Breathing, Fourth Form: Shifting Flow Slash; he speeds towards the demon and slashes, only to miss and find Hantengu now on the ceiling with a small cut, begging them to stop "tormenting" him as he heals. Putting aside his nerves and quickly breathing with the style, Tanjiro uses Hinokami Kagura: Sunflower Thrust, yet he too fails to make contact with Hantengu, now on the floor; he becomes more confused seeing that the demon is not fighting back. Growing in size, Nezuko lands a powerful kick on the demon, slamming him into the wall, but Tanjiro warns her against using the form, as it will only further her transformation into a full demon. With the demon stunned by the kick, Muichiro sees his chance and beheads Hantengu.

However, remembering that beheading alone does not kill Upper Rank demons, Tanjiro warns Muichiro to keep him alert. Without warning, the demon’s severed head changes appearance and grows a new body, while the headless body gains a new head and form. Tanjiro decides to take the standing demon, while Muichiro attacks the one in front of him. Before he can reach it with his blade, the demon uses a leaf-shaped uchiwa and blasts the Mist Hashira away with a powerful gust of wind, further destroying the room and forcing Nezuko to hold Tanjiro down from flying away as well. The uchiwa-wielding manifestation of pleasure laughs at Muichiro flying away, asking his fellow demon Sekido if he agrees. The manifestation of anger states that he did not find it fun and angrily rants at the demon, Karaku, on having to be joined with him. As Tanjiro attempts to plan an attack on the two, Sekido wields his khakkhara and summons bolts of electricity, paralyzing the siblings in place. As Tanjiro reels from the attack and almost loses consciousness, he sees someone on the roof above them.

Using a hand-held double barrel shotgun, Genya fires Nichirin steel shot at the demons, beheading Sekido but partially severing Karaku’s neck. Using his blade, he runs down to finish the second demon off, who finds enjoyment in a new attack on him. As Genya beheads Karaku, Tanjiro attempts to warn him that the demons cannot be defeated if they want him to behead them.

As the demons heal and form new bodies and heads, Tanjiro realizes that beheading them is not how they can be killed but cannot seem to find a weak spot, seeing as they all heal at the same rate. With all opponents now reveal, he notices one seems to be missing but is suddenly pulled up by the missing winged demon, Nezuko unable to reach him in time. Tanjiro tells her to help Genya instead but becomes horrified to see him impaled by a spear-wielding demon. The winged demon insults him for caring about others but himself and prepares to attack. The Demon Slayer attempts to use Hinokami Kagura but is hit by a powerful sonic shriek that causes him to bleed, only cutting the demon’s leg holding him. As he falls, Tanjiro attempts to grab a tree branch but fails and lands hard on the ground. As he urges himself to get up and save the villages, he feels his body is now numb and due to the attack, he cannot hear anything. Suddenly, he realizes that the demon’s leg is still holding and turns to see a new head about to unleash the sonic strike once again.

Having landed safely, albeit a great distance away, Muichiro runs back to aid Tanjiro with the demon but sees a fish-like demon attempting to eat Kotetsu. Seeing he is a child with no swordsmanship skills, he deems helping him to be of low priority and continues on his way. Surmising that the demon is not the main body but one made with a technique, he rationalizes finding the main body to be of paramount urgency and notes that when the village is attacked, the most important mission is protecting the chief, as the demon grabs hold of Kotetsu. The Hashira then remembers Tanjiro’s words about helping others eventually benefitting him, causing Muichiro to stop in his tracks. As the fish demon squeezes Kotetsu unconscious, its arm is sliced off and frees the young swordsmith of its hold. Muichiro rushes in and takes a stance in front of Kotetsu, asking him to run away as he will only get in the way of his fighting.