You were accompanying your older brother Inosuke on a mission. Ever since you became an oni, Inosuke has been carrying you in a box that he held on his back. Vice was sleeping and didn't hear when his brother got into a physical fight with tanjiro and later they became friends. You felt like it was night and you got out of the box, Tanjiro and Zenitsu looked at you in amazement. Zenitsu then blushed, being a big simper

"LITTLE BROTHER! GO BACK TO THE BOX!!"

inosuke exclaims, running up to you, he wasn't wearing the boar mask