Muzan Kibutsuji recounts how death had always been close to him and that his heart had stopped many times even while he had been inside his mother's womb. He had been stillborn but when he was about to be cremated, he suddenly began writhing around and crying for the first time and thus had been spared.
The Demon feels relieved as he says that he had finally achieved what he had been waiting to make happen for so long. Admitting that what he could do on his own was limited, he thinks of Kagaya Ubuyashiki and concedes that what the Oyakata had told him was correct. Saying that everything that lives must die and that only feelings were eternal, Muzan says that he did not remember even a single human being he had killed but their feelings had been passed on and had stayed alive, even managing to conquer him.
Being moved to tears at the fact that the feelings of all the people had vanquished him, Muzan is resigned to his inevitable fate. However, he says that his own feelings are eternal and undying just like anyone else's and he extends his hand towards Tanjiro Kamado who was there with him and still alive.
As he gives all of his blood to Tanjiro, Muzan says that if the boy survived this he would become the strongest Demon ever. Since he was the brother of Nezuko Kamado who was the first Demon to develop an immunity to sunlight and also the only one capable of using the Breath Style of Yoriichi Tsugikuni. As he slowly disintegrates, Muzan tells Tanjiro to make his dream come true and destroy the Demon Slayer Corps in his place.
As Giyu Tomioka kneels in front of Tanjiro and the surrounding Kakushi shed tears, one of them suddenly gapes in shock as the tumour from Tanjiro's head disappears and he opens his eyes to reveal a Demonic gaze. To everyone's shock Tanjiro regenerates his left arm and swipes at the Kakushi next to him but Giyu reacts quickly and pushes the Kakushi out of harm's way.
The other Kakushi look on in fear and ask Tanjiro why he is acting in such a manner, as the boy stands drooling profusely, enjoying his newfound fangs and claws. His Demon Slayer Mark mutates and grows down to move past the bridge of his nose, with another identical mark growing upwards from his neck to almost meet the other, similar to Kokushibo's Mark.
Giyu rushes forward and yells at the other Kakushi to get away from Tanjiro as the boy looks to swipe at him. Suddenly, the sun shines brightly from the sky and Tanjiro double takes to look at it. He begins to burn and writhes on the ground, with his swipe at the Kakushi going off target but still managing to rip off the lower half of his mask. As Giyu gets in front of the Kakushi, he tells him to run away as he prepares to face this new threat, yelling for anyone who was still conscious to grab a weapon and begin fighting.
Everyone else looks on from afar with confusion at the sudden commotion, unaware of Tanjiro's fate when Giyu suddenly announces to them that Tanjiro has become a Demon. He says that they need to pin Tanjiro down and burn him in the sun before he could kill anyone. Tanjiro suddenly attempts to find shade to stop burning but Giyu intercepts him by stabbing him from the side and dragging him to ground, with the boy clutching at his hair. Noting to himself that if he had not been interrupted by the sun, Tanjiro would have surely killed the Kakushi, Giyu wistfully begs in his mind for Tanjiro to stay who he was and die as a human.
Suddenly, Tanjiro stops burning and Giyu looks on in shock as the boy takes advantage of the Hashira's surprise to swipe at him. Giyu narrowly dodges but his chin is grazed as Tanjiro follows up with another swipe that is intercepted by Inosuke Hashibira who yells his friend and asks him what he is doing. Giyu attempts to stand up but feels dizzy from his blood loss and cannot do so.
Inosuke stands over him and tries to remind Tanjiro that Giyu is their ally as Zenitsu Agatsuma approaches the scene, supported by a Kakushi. Tanjiro crouches down and a third Demon Slayer Mark appears from the other side of his head and he bares his fangs at Inosuke who can only look on quietly at what his become of his friend. Zenitsu looks on in disbelief at the scene and says that everyone is tired and unable to continue fighting, asking for Tanjiro to think of Nezuko. Tanjiro leaps forward to attack Inosuke who prepares to fight him.
Inosuke thinks back to his time together with Tanjiro and says that they are all comrades, like brothers who would pull each other back if one of them started going down the wrong path. Steeling himself by thinking that no matter how difficult it was, they would always walk the right path. Zenitsu yells at Tanjiro to stop as Inosuke thinks to himself that he would strike Tanjiro down and stop him. Suddenly hit by a memory of Tanjiro offering him some fish to eat together with a smile on his face, Inosuke stops mid-swipe at Tanjiro's neck and is unable to complete his attack, tearing up and saying it was no use and that he could not attack Tanjiro.
Characters in Order of Appearance
- Tanjiro Kamado
- Giyu Tomioka
- Muzan Kibutsuji
- Inosuke Hashibira
- Zenitsu Agatsuma
- Sanemi Shinazugawa
- Kagaya Ubuyashiki (flashback)
- Nezuko Kamado (flashback)
- Muzan injects Tanjiro with all of his blood, turning him into a demon.
- Tanjiro begins to become immune to sunlight.
- Inosuke finds himself incapable of taking a killing strike at Tanjiro.