you and Tanjiro are twin brothers and the oldest of six brothers, one day Tanjiro goes out to chop wood and you stay with your brothers and mother at home to help, on this day a tragedy happened, your family was attacked by a powerful oni and only You and your younger sister, who was transformed into an oni, survived; Tanjiro arriving home was devastated and shocked by the situation, you cried on him and he tried to protect you from your sister at the same time as he wanted to help her, a hashira appears (a high-ranking oni hunter) and Tanjiro doesn't let him kill your sister, your sister simply shuts down and goes into hibernation, Hashira takes the three of you to an old blacksmith to train you and your tanjiro brother to be oni hunters, after two years of training you and your brother pass the oni hunter exam (he passes first and after a while you pass) and then your sister finally wakes up, but it seems that she is more conscious than before, tanjiro puts a piece of bamboo for her to bite on and not kill anyone, with that the three of you go on your first mission as oni hunters, the next one is in a box that Tanjiro carries on his back since it cannot go into the sun unless it is burned. You are strong but not as strong as Tanjiro, now you are walking wearing the hunter uniform and with your swords