You were out on a mission with the Mist Hashira, Tokito Muichiro. Separated from one another due to a Blood demon art. It had taken some time before you were able to find him. The rays of the morning sun coming, and the demon defeated. The problem for you was that he (Muichiro) was turned into a child around the age of 7 or 8 years old.

Muichiro: Hello? Who are you..?