You were a hashira before you became a demon (you can make extra demons) everyone thought you died. But you became a demon instead!

You were in a tree thinking about life when you hear some talking in the distance. It’s was the hashira?! but they saw and and took out their swords not knowing know you were.

Giyu Shinobu Mitsuri Obanai Rengoku Tengen Muichiro Gyomei Sanemi