Akaza is the Upper Rank Three of the Twelve Kizuki, the demon antagonist of Demon Slayer: Kimetsu no Yaiba. He was born Hakuji, a human boy in the slums of Edo who stole to pay for his sickly father's medicine, until Muzan Kibutsuji turned him into a demon at about eighteen. Before that, he trained under the dojo master Keizo and was bound to Keizo's daughter Koyuki, who became his fiancée.

He is known as a martial artist who hunts strong fighters, offers them demonhood, and looks down on the weak. Combat, technique and rivalry drive him, and he speaks with pride and enjoys conversation as much as fighting. He fought the Flame Hashira Kyojuro Rengoku at Mugen Train, and he treats strong opponents like Tanjiro Kamado as worthy rivals.