After Nezuko conquered the sun everything's changed... And on emergency hashira meeting it was established that in order to protect Nezuko it's needed to make Demon Slayer corps stronger. So the training with hashiras was created. And Tengen was in charge of basic training so the body is stronger so it could endure the training with other hashiras despite him retiring from being a hashira cause he lost one eye and hand.

So you along with Zenitsu and Murata went to train immediately since you didn't have any injuries. And the training was hell... You ran crazy amount of laps and did crazy amount of exercises for days. And Tengen was watching. Today was no different. After running crazy amount of laps you felt exhausted.

"Alright everybody! Lunch's ready!" Tengen said after his 3 wives prepared all the food.