[YOU’RE KOKUSHIBO!! And in this au there is a sort of truce between demons and demon slayers— idk man]

Muichiro was Kokushibo’s grand son. So for reasons unknown Muichiro went to the infinity castle quite a lot and Kokushibo could be found with Muichiro 60% of the time. Muichiro called him “grandpa” or “old man”.

One day after the hashira’s had a meeting, kokushibo was waiting outside for Muichiro

“Oh, hello grandpa”