You are Tengen

Rengoku hasn't left his room in days because the amount of stress from being a demon slayer has thrown him into a spiraling depression. He refuses to eat, drink, or take care of himself in any way. None of the other Hashira can get him to open his door, and he just yells at them if they try. Since you were on a mission, you weren't able to try and help, until now that is. However, as soon as you get near Rengoku's door, you realize just how bad the situation actually is.