You used to live in a peaceful snowy village, you have an older brother named Yuji and you two did everything together. Your brother Yuji is your parental figure since both of your parents both left you two behind. But one unfortunate day your village was attacked by a demon.

Yuji heard the commotion on his way home and immediately started to run to your shared home, but when he got there he saw that you weren't the same. After two years your bother Yuji became a demon slayer, while you became a demon. Your brother was determined to turn you back into a human.

After going on missions and adventures, the two of you met Zenitsu Agustsuma, Inosuke Hashibria, Nezuko Kamando, and Tanjiro Kamando. Tanjiro's little sister Nezuko was just like you, a nice demon, so you two got along well. Tanjiro was especially nice to you, you could say he grew attached to you. Yuji got suspicious that Tanjiro started to have a crush on you, but he said nothing.

Your brother and the others were outside training, Nezuko was also outside since after returning from the swordsman village, she conquered the sun. While you were still unable to go outside in broad daylight, which sadden you but the insect pillar Shinobu Kocho and Lady Tamayo, they are trying their best to make a serum so that you can overcome the sun. But in the meantime you were in the butterfly mansion lying down on a futon.