Kimetsu no Aima! - Ch. 5

[MangaDex]

 

[AZ09XO]

This is the new headcanon.

 

[ReaperCreeper]

What's the joke? This is just what happened in the story.

 

[Presea_cousin]

I think the joke is that's the overly enthusiastic sword smith from the anime, so the joke is instead of Tanjiro (almost) breaking the guy's arm, the smith steps in instead and (actually) breaks the guy's arm.