Demon Slayer Backstory's (Cannon)

Akaza

Word Count : 743

When Akaza was human, his name was Hakuji. He was born and raised in the slums to a sickly father he deeply loved. In order to pay for medicine, Hakuji pickpocketed people in town but was caught three times, every time he was caught he was beaten badly, and the last time he was caught he was arrested. The magistrate beat him and marked him with tattoos, threatening to cut his arms off the next time he was caught and calling him a "Demon Child" When Hakuji's father got word that his only son was arrested for pickpocketing people he hung himself leaving his son a note. When Hakuji returned home he found his father hanging with a note below him, and with great sorrow, he picked up the note and read "he wanted Hakuji to live a full life and didn't want to take medicine if it was earned by dishonest means" 

With his criminal tattoos and no home to return to, Hakuji was eventually banished from Edo. Devastated by the loss of his father and enraged at this society they lived in where he couldn't afford his father's medicine, he picked fights with people and beat them up. One of these times Hakuji beat and almost killed seven men from the village and was found by Keizo, the owner of a local dojo. He walked up to Hakuji with a smile and started small talk not caring about the seven half-dead men laying on the ground. Annoyed by the man's cheerful demeanor, Hakuji challenged him to a fight but was defeated with ease. That day Keizo took Hakuji to his house so that he would take care of his sickly daughter, Koyuki. Her mother, her previous caretaker, drowned herself due to stress and Keizo had to work handyman jobs to keep them afloat, so Hakuji was tasked with tending to her. Already accustomed to caring for his father, he had little trouble, though he found it awkward when she burst into tears seemingly at random. 

One day, he discovered that Koyuki had been forced outside and left there by the heir of the nearby kenjutsu dojo that sought Keizo's land for themselves. Because of this, they prevented Keizo from getting any students before Hakuji. Enraged, Keizo and Hakuji fought the dojo, and after defeating nine people, Hakuji made them promise to never get involved with the Soryuu dojo or Koyuki again. The heir of the rival dojo became enraged and swung a sword at Hakuji, only for Hakuji to use his Bell Splitter technique and punch the side of the blade, breaking it. The other members of the dojo were so moved by the beauty of this technique that they accepted their loss and apologized for the rudeness of the heir, leaving the Soryuu dojo in peace. 

Two years later, Koyuki's health improved enough that she could stand and do chores. Hakuji continued training as Keizo's pupil of the Soryu style, and the dojo began to grow. One day, Keizo offered to let Hakuji take over the dojo—and take Koyuki as his bride, to Hakuji's surprise and embarrassment. He agreed, silently vowing to protect both of them, even at the cost of his own life. At a festival, Koyuki told him of her past, asking if he was really okay with the proposal, to which he reaffirmed his vows to her, promising to protect her for the rest of his life.

The heir of the rival dojo heard about Hakuji's marriage to Koyuki, so he gathered some angered disciples and fought Hakuji, but they lost. Tragically, this victory was short-lived. Hakuji went to visit his father's grave to inform him of his marriage but quickly realized something was amiss upon his return. A student from the dojo informed him that the rival dojo had poisoned the well where Koyuki and Keizo drank water from. The two died shortly after drinking that water while Hakuji had been away. Enraged with this act Hakuji found and slaughtered all Sixty-seven members with his bare hands. This massacre was noticed by Muzan Kibutsuji who went to sight, when he got there he was disappointed to find it was a human and not a demon that killed all the men but was happy to offer Hakuji a chance to become a demon. With nothing left for him, Hakuji agreed to the offer and took Muzans blood, and began the transformation, becoming the demon Akaza.