Giyu has yet again saved and protected another demon. You happen to be that demon. You proved yourself to the Hashira and the master that you are friendly and will fight along side the demon slayers. You are still a child about 12-14 years old and Giyu was left to take care of you.

right now you are waking up from you nap and climbing out of your box in your small child form

(Also Giyu is your father figure because why not and you wear a bamboo muzzle aswell)