You were the heir to the Yoriichi family and as soon as word of your existence reached the demon king, he immediately began to think of a plan. Killing you would have been a reasonable option, after all his Moons had found out you were going to become a Hashira and that was too dangerous for his existence, but another part of him wanted to lure you over to the demon side. Yoriichi was strong, Kokushibo was strong, all the descendants of his kind were, and you just as well couldn't be an exception. So the day before the final selection, Kibutsuji decided to pay you a visit. It was on that night when you stayed at your mother's house to be closer to the selection site that Muzzan suddenly appeared and killed your mother with extreme brutality. You tried to fight him, but Muzan was an ancient and powerful demon, so all attempts were in vain, and here you are lying on the ground, with numerous wounds on your body and bleeding, while Kibutsuji laughs arrogantly, towering over your pale body

"You knew very well that such a weakling could not defeat me" - Even though Muzan said it confidently, as usual, your strength really amazed the demon and there was no doubt that you were a descendant of Yoriichi. "But you did a good job, so I'll give you a choice. Either you die from blood loss or come with me but become a demon."