Hakuji asks himself why sick people are always apologizing, remembering the times his father did so and Koyuki now apologizing that he can't train while caring for her. Koyuki was born with a weak body and had to be attended to day and night. However, Hakuji was fine with the task; he previously cared for his ill father and his resilient nature meant he never tired. He never felt like playing around anyway and simply trained in his free time. Hakuji mentions there would be fireworks on display and that he was willing to carry her to the bridge to watch with him. When Koyuki seems unsure, he reminds her of next year, and the year after that. She begins to cry, somewhat annoying him that she would burst into tears mid-conversation. He believes she cries due to the depressing nature of her illness, while commenting her crying made him uncomfortable.
Keizo and Hakuji share a drink at the well, the master mentioning how their names are similarly structured to be based on a phrase meaning protect. Therefore, they must protect something, a fact that makes Keizo laugh. Keizo recalls how the dojo came to be. His former master had protected an old man with the Soryu style of combat. Amazed at the feat, the man gave him his land as a place for a dojo. Later on however, the nearby Kenjutsu Dojo began to harassed the Soryu dojo, leading to him having no students. This was mitigated in Keizo's eyes by training Hakuji and caring for Koyuki, something he said healed his heart.
Years later, Hakuji turns eighteen and Koyuki turns sixteen, Koyuki no longer needing to continually lie down and is now bright and happy. While cleaning the floors, Hakuji was summoned to the dojo and spoke with Keizo. He wants him to take over care of the dojo, casually mentioning he can have Koyuki as well, a statement shocking both of them. Hakuji never believed he could have a future as a criminal, much less a future as a husband with a wife. He remembers his father's letter to him, and recalls the swelling feeling his life could go anywhere, declaring now he wants nothing more than to protect Koyuki and Keizo, even at the cost of his life.
Hakuji travels back home to tell his father's grave about his marriage. But as he returned to the dojo, he suddenly began to breathe heavily and a sinking feeling came over him. Someone informs him the well they drank from was poisoned by the Kenjutsu Dojo, killing Keizo and Koyuki. Seeing their bloodied, lifeless bodies at the dojo floor, Hakuji laments he's never there to protect his loved ones in a crisis. He suddenly remembers a moment back when Koyuki came with him to watch the village's new year fireworks. Koyuki asks about the conversation they had about fireworks while they were young, something he had forgotten, something she never forgot. When she was unable to watch them that year, he suggested the next one, and the one after that. She recalls when she didn't believe in herself living another year or so on. Koyuki remembers when her mother killed herself being unable to care for her any longer, and believed, in a way, her father too was tired of caring for her as well. She saw Hakuji casually asking if she was willing to see them next year, giving her the hope of a future. Koyuki asks if he would like to be her husband. Hakuji graciously answers so, "Yes, I will become stronger than anyone else and protect you for my entire life". In the end, Akaza laments it was simply just words, he couldn't manage anything in his life.
Filled with rage and losing the people he loved once again, Hakuji went to the Kenjutsu Dojo and brutally killed all sixty seven masters inside. Using the Soryuu style, he eviscerated their bodies; the dojo was found with crushed skulls, destroyed organs, brain, limbs and eyeballs strewn throughout the building, all the corpses destroyed to the point they were unrecognizable as a human body. The incident was so horrific and absurd, it was regarded as a fictional story before being erased from history. In the wake of the destruction, a bloodied and broken Hakuji encounters Muzan Kibutsuji. Muzan had heard about the carnage and mistakenly thought he sent a demon to do so, instead finding a human had done it, leaving him disappointed. Hakuji threatened to kill him when the Demon Lord suddenly rushed forward and pierced his head with his hand before he could fight back. Muzan comments he was thinking about building a group of twelve powerful demons and asks Hakuji if he could withstand the amount of blood he was to be given. Hakuji declares he no longer cares about anything anymore and transformed into the demon Akaza.
Akaza recalls losing his human memories in the wake of turning into a demon but continue to have the drive to get stronger and stronger. Though he had nothing to protect, he somehow wishes to live in a world where he lost his family but nonetheless continued to murder people for the next 100 years. In the end, Akaza comments once more his life was nothing but a pathetic, comical, uninteresting story.