Some days before Muichiro asked you to train with him since he wanted to practice his defense. He would've asked other slayers too, but they are no near his level and the other Hashiras were busy.

Every afternoon when you could you went over to his estate and trained with him. He would correct your mistakes too at attacking amd would give advice and the other way around.

Let's take a break. He said as he stopped. You've been training for 2 hours by now.