Members from the Hashira of the Demon Slayer Corps have arrived on Mount Natagumo.
Giyu Tomioka, the Water Hashira, slays the father of the Spider Demons with a single stroke of his sword. Inosuke, thrilled to see such a display of swordsmanship by someone in a completely different league from himself, challenges Giyu to a duel.
Meanwhile, the Insect Hashira, Shinobu Kocho, appears in front of Zenitsu, who lies near death as the poison circulates throughout his body…
As Tanjiro attempts to slash the incoming thread with his sword, it slices cleanly through the steel; he is barely able to dodge it and sustains a cut across his face. As he stares in shock seeing his weapon destroyed, Rui looks at his downed opponent.
Inosuke watches as Father’s dismembered body fades to ash, amazed by the strength and power of Giyu; he turns and sees an excited Inosuke, giving him a confused expression before leaving. Inosuke demands he stop walking away; he declares to his saviour that since he had beaten a Twelve Kizuki, he will defeat him and then become the most powerful Demon Slayer. Giyu only tells him to go back training, infuriating the masked Demon Slayer.
Giyu states that Father is nothing close to a Twelve Kizuki, while unwinding a bundle of rope. Inosuke retorts his statement and claims he was right that Father wasn’t a Kizuki demon. He claims it was Tanjiro who said so but suddenly finds himself tied to a tree. Stunned by his sudden speed, he watches as Giyu walks away and leaves him hanging. He tells him to stay out of battle if he can’t realize his own injuries, causing Inosuke to yell at him to come back.
At the suspended house, Zenitsu sees Shinobu asking if he is alright; he mutters “Gramps”, causing her to ask who is he calling to. Zenitsu says he appeared and told him not to give up. Shinobu tells him it was because he is seeing his life flash before him, stating it was probably a way for his body to avoid dying; by going through past memories. Shinobu states she doesn’t know for sure; she instead commends him for slowing the poison’s circulation with his breathing. She injects his now shrunken arm with an antidote. Zenitsu turns his head and sees numerous black-clad workers helping the transformed Demon Slayers.
As Tanjiro continues his battle with Rui, he notes that his threads are even stronger than Father’s body, whom he was unable to cut through. Realizing his inexperience had led his sword to breaking, he apologizes to Urokodaki and Haganezuka. Rui launches several threads at him but Tanjiro is able to dodge them. He thinks of a plan but the threads continue to prevent him from getting close. Rui asks if he still refuses to take back his words and Tanjiro shows his defiance. With his answer, the demon goes for the kill and launches his threads in the form of webs, ready to slice Tanjiro to pieces. Before they hit him, something makes contact with the webs; Nezuko appears in front of him and takes the hit, sustaining deep cuts. Tanjiro is shocked and pulls her to safety to inspect her wounds.
As Daughter notes that she has the aura of a demon, Rui begins to shudder at what he has witnessed; he asks if the girl is his sibling; Tanjiro answers that it doesn’t matter to him, as he sees Nezuko’s sliced hand about to fall off. Rui realizes that Tanjiro’s sister has transformed into a demon, yet protected him regardless; the younger sibling protecting the older sibling, the genuine bond that he has longed for. Daughter sees his sudden change in personality and tells him she is his elder sister, asking him not to desert her. Rui angrily dismisses her and launches several threads, slicing her body to pieces. Rui claims that, “none of you ever managed to fulfill the roles you were given”, rejecting his “family”. She claims she became the sister he had wanted, asking for a chance at redemption. Rui decides to relent, giving her the task of killing the Demon Slayers on the mountain and promising to forgive her when she does. Daughter acknowledges his wishes and leaves.
Rui calls out to Tanjiro and claims he was moved seeing the bond between him and his sister. With nothing left but death for Tanjiro, Rui gives him an ultimatum; hand over Nezuko and he will spare his life. When Tanjiro states he doesn’t understand what he wants, Rui tells him she will be his new sister, starting now. He vehemently refuses, saying that she isn’t a thing and that she has her own feeling and will. The demon responds by claiming he can make a bond between them, one built on terror, since he is much stronger than him.
Tanjiro raises his blade in anger and states that using fear to hold someone isn’t a familial bond. He retorts his lack of understanding will lead him to never getting what he wants. Rui becomes irritated by his loud rebuttal and claims they don’t see at the same level. Putting aside Nezuko’s box, Tanjiro walks out of the bushes and faces his opponent, telling him that “I’ll never hand Nezuko over to you!”. When Rui claims he can just kill him and take her then, the Demon Slayer states he will cut off his head first. Rui becomes excited at his spirit and states he can try, then reveals the engraved number on his eye, the mark of Lower Rank Five.
Rui thinks about his demon family and their roles; the parents protect the children and the elder siblings protect the youngest sibling, even at the cost of their lives. To him, not understanding that role give you no reason to live. He states that Tanjiro’s role is to give him Nezuko, and he cannot defy it because he cannot kill him. Tanjiro realizes his opponent is a true Twelve Kizuki, thinking how could he defeat him with his broken blade if his neck is tougher than his threads. Rui sees the hopeful glimmer in his eyes, calling him foolish for believing he has a chance at killing him.
He pulls on several threads behind Tanjiro and takes Nezuko before his eyes. He grabs her and asks if he now recognizes his own role. Tanjiro demands he let her go, with Rui reminding him that he offered to spare him if he doesn’t fight back; Nezuko angrily claws at his face in defiance. As the Demon Slayer gets closer, Lower Five flings several threads him, forcing him back. He sees that Nezuko has vanished; when a splash of blood falls on his blade, he looks up and sees her strung up in the trees, with horrific cuts throughout her body.
Rui tells him not to be shocked, as Nezuko is a demon and she can heal; he then decides to string her up to “teach her a lesson” and let her bleed. As Tanjiro seethes with rage, he adds that he might leave her till dawn and “let her roast a bit”. Tanjiro attacks the demon but is stopped by several threads slowing his approach. Rui kicks him in the face, launching him high into the air and causing him to vomit blood. Rui smacks him with his hand and Tanjiro staggers in pain, bleeding heavily. The Lower Rank taunts him for thinking he could kill him and openly accepts an attempt to decapitate him.
In desperation, Tanjiro attempts to slice his neck but finds his blade unable to cut through Rui’s skin. Rui reminds him again that he has no chance to win and violently kicks him across the forest floor, stating his body is more durable than his threads; Nezuko, watching the confrontation, struggles and squirms in her restraints to help him, as Tanjiro realizes this is the true power of a Twelve Kizuki. Annoyed by her screaming, Rui tightens the threads holding her and they cut deeper into her body, making her scream. Nezuko loses consciousness, to Rui’s confusion, as he notes that something about her is different to other demons.
Despite being enraged, Tanjiro calms himself down and decides to use the final and most precise form at his disposal. Lunging at the demon with renewed speed, he successfully parries the threads by gathering momentum in each swing. He uses Water Breathing, Tenth Form: Constant Flux and is able to slice through the threads, giving him the motivation to defeat the demon. Undaunted, Rui reveals his threads aren't at maximum strength and infuses new ones with his blood. Using Blood Demon Art: Cutting Thread Cage, he surrounds Tanjiro in a web of blood threads to shred him, bidding him goodbye as they close in. Surrounded and unable to cut through the new threads, Tanjiro realizes he will die and suddenly sees his life flash before him.
In a web of pivotal memories, one moment stands out. In a memory during his childhood, playing and dancing with Nezuko, he sees his father, who tells him to, “Breathe. Get your breathing under control and become Hinokami”. He then remembers being with his mother outside on a cold wintery day, watching his father’s ceremonial kagura. She explains that in a family that works with fire, he performs this ritual to “Hinokami” to ward off disasters. Tanjiro then asks how he can dance for so long in the snow despite being so frail.
In another time, his father Tanjuro answers that he uses a special breathing technique; one that can allow you to move without ever exhausting yourself. If he can master it, he can dance forever and even ignore the cold. Tanjuro then asks for his son to, if nothing else, pass the kagura and his earrings down to his descendants, as he had promised before.
After gathering the knowledge from his memories, Tanjiro begins to breathe in a different pattern; his Water Breathing ignites into fire as he uses his new Hinokami Kagura, using the form Dance to slice through the blood threads. Seeing his stronger threads cut, Rui deploys more threads and strews them in front of the Demon Slayer’s path. Though he sustains several cuts, Tanjiro continues to press onwards, aware that stopping now after switching between Water Breathing and Hinokami Kagura will render him immobile.
Pushing himself to rescue Nezuko, Tanjiro attacks Lower Rank Five with renewed ferocity, slicing the blood threads in his way as he closes in on Rui. Shocked, Rui backs away and is forced to defend himself, weaving around the forest to escape. He tries to use more blood threads but Tanjiro is now able to chase him down and cut through them all. He detects the Opening Thread and sees his chance to slice off his neck, ignoring the threads now close to cutting into him.
As Nezuko hangs in the threads, she is visited by a vision of her mother. Kie begs her to wake up and save Tanjiro. She says she can do it and do her best. She tearfully asks for her to awaken, “Or your brother will be killed too!”. At that moment, Nezuko regains consciousness and stretching out her hand, causing drops of her blood on the threads to glow. Using her own Blood Demon Art, Exploding Blood, she ignites her blood and the threads burn away.
The flames race down the webs, reaching Rui and Tanjiro; the fires burn away the threads in Tanjiro’s path and allows his blade to make contact with Rui’s neck. In disbelief, the demon can only watch as the Demon Slayer proclaims, “The bond between Nezuko and me can’t be severed by anyone!”. As the drops of blood on his blade ignites, Tanjiro slices through Rui’s neck, decapitating Lower Rank Five.
Characters in Order of Appearance