Who Injured Yonko Hundred-Beast Kaidou?

 I couldn't hold onto my chair when Oda [sensei] revealed to us the last Yonko, Hundred-Beast Kaidou. After a minor disappointment with Big Mam--although I did expect a super sized being--Kaidou was just what is expected of the top of the crème, one of the Yonko. A beast whose aura gives away sheer power.

Now, the reason for this short post is to figure out what happened or who caused the injury on Kaidou's stomach.

 You see it?


Who could have possibly inflicted such an injury on the body of the Strongest Living Creature?

Well here are my usual suspects: