"I'm home, father. I'm home, master. Koyuki, I'm back."During the battle at the Infinity Castle, Akaza ambushes Tanjiro and Giyu. He immediately goes after Tanjiro, but the latter's drastic improvement allows him to hold his own against the upper moon. Akaza recognizes Tanjiro's growth and acknowledges it before reengaging Tanjiro and Giyu. Despite it being 2 on 1 Akaza overpowers the pair and explains his disgust for the weak, infuriating Tanjiro, who counters with his own beliefs that the strong should protect the weak. Tanjiro's words briefly remind Akaza of his forgotten memories as a human, angering him to point he attacks the memory of Keizo despite nothing being there. Akaza intensifies his attacks and using his powerful instincts to detect killing intent and perceive attacks, overpowers him. He grabs Tanjiro's sword and tries to break it, but is stopped by Giyu, who awakens his demon slayer mark. While Giyu holds Akaza back Tanjiro realizes from a previous conversation with Inosuke how Akaza is foreseeing all their attacks and how to eliminate his own killing intent using a technique called "transparent world" from a memory of his father. Despite utilizing his demon slayer mark, Giyu is still unable to defeat Akaza because of his battle sense. Akaza eventually breaks his sword and seemingly impales Giyu, but in actuality, Tanjiro cut off his hand with his new technique before he could kill Giyu. Akaza then unleashes his strongest technique and overpowers Giyu and approaches him to kill him. However, Tanjiro gets behind Akaza without him noticing, but instead of killing him with a surprise attack, Tanjiro deliberately makes himself known and declares he shall decapitate him. Akaza tries to kill Tanjiro, believing his battle sense will give him the edge, but discovers Tanjiro's killing intent has vanished, making his sense useless. In that moment Tanjiro completely surpasses Akaza's speed and senses then decapitates him with the very technique he has been striving to achieve. However, Akaza refuses to submit and tries to resist death by putting his head back on, only for Giyu to knock it off by impaling it with his sword. As Akaza's head hits the ground and disintegrates, his thoughts focus solely on getting stronger and his body doesn't disintegrate and keeps attacking the weakened Tanjiro. Tanjiro passes out from overexertion and Giyu desperately tries to protect him. As Akaza tries to continue fighting, he is held back by the spirit of Koyuki.As Koyuki's spirit holds Akaza back, she asks him why he still seeks to becomes stronger. Akaza begins to remember his past and answers that if he isn't strong enough, he won't be able to steal the medicine his sick father needs. Akaza remembers his past as a thief trying to tend to his ailing father, becoming Keizo's student, falling in love with Koyuki, and ruthlessly murdering those responsible for his loved ones' murder with his bare hands before being turned into a demon. After remembering Akaza's consciousness returned to that of Hakuji, but his body begins to regenerate its head and attacks again. Unwilling to resume being a demon and acknowledging his defeat at Tanjiro's hands, Hakuji takes back control of his body and has it destroy itself. Hakuji begins passing to the afterlife where he meets his father and Keizo, who forgive him for his crimes. Muzan's spirit appears and tries to return Hakuji to being Akaza, but Koyuki's spirit pulls out away from Muzan's influence for good and the two reunite as Akaza is sent to hell, finally reunited with his loved ones.Akaza was the only demon of the Twelve Kizuki who refused to eat or kill women, and was given special permission to do so by Muzan, although he did tease Akaza for his choice and urged him to drop it. Doma in response complained that Akaza got special treatment