As Akaza laments he cannot go to heaven like his father, Keizo and Koyuki, he becomes furious that Tanjiro and Giyu have reminded him of his painful past. He curses humans as weak, soft, brittle, they die right away, they're brittle and disappear into nothing. Tanjiro awakens from his ordeal, shocked at how he fainted mid-battle. As Akaza begins to regenerate his head, he begins to deploy his Annihilation Type. As Tanjiro yells at him to stop, the demon becomes shocked that Tanjiro has manage to survive his kick. Declaring he will behead Akaza again, Tanjiro's sword ignites with the fires of the Hinokami Kagura.
However, his sword slips out of his grasp, forcing Tanjiro to punch Akaza's face instead. The punch reminds him of when he first met Keizo, making him remember why he hates weak people. Weak people never fight face to face, they poison wells, they're impatient. He killed these weak people with his fists. He suddenly realises throughout his life as a demon, he turned his master's fighting style into a bloody weapon and never respected his father's last words, finally realising who he must truly kill. As Tanjiro panics about his lost sword and seeing Akaza about to use the same technique that killed Rengoku, he suddenly notices Giyu in the attack's range. Though Giyu tells to not worry about him, Tanjiro grabs him and throws both themselves out of the technique's path.
Suddenly, he sees Akaza, smiling slightly, followed by an immense explosion. The attack leaves the surroundings devastated, as well as Akaza's body, now a broken, bloody mess. Wondering why Akaza would attack himself, Tanjiro smells a scent of gratitude from the corpse, as well as asking himself why he had smiled before hitting himself. The body begins to regenerate, but Akaza stops the process, telling himself the fight is over, he had lost fair and square. He comments Tanjiro had magnificent technique, anticipating and slashing before he could react. The broken body begins to walk away, while Akaza's spirit comments he would go to hell as a man. When he stops, to Tanjiro's confusion, his spirit meets with his father's.
Asking if he was alright, his father comments yes, calling him Hakuji and thanking him. As he bows and crouches down, apologising for being unable to fix himself, his head is held by Keizo's spirit. Keizo tells him that they would never abandon him, no matter what, despite Akaza not being able to go to heaven with them. As he calls out for his master, Muzan appears, grabs his head and scolds him, reminding him to get stronger and continue fighting. With that, his body regenerates even quicker. Akaza voices his will to keep his promise and get stronger, declaring once again he will kill everyone. Suddenly, Koyuki touches his face, thanking Hakuji and saying that he has done enough. Though Muzan appears again, calling him Akaza once more, he overcomes Muzan's control and grabs Koyuki's spirit on the verge of tears, once again the human Hakuji.
He tearfully apologizes for being unable to protect her, for not being there when she need him, for not being able to keep his promise. Crying for forgiveness, Koyuki is glad that Hakuji had remembered them all despite his long, demon life and returning as a human again. With the words, "Welcome back, my husband", Akaza stops his regeneration. Tanjiro watches as his body finally fades into ash.