One Piece: The Wano Arc
The story resumes from the journey of the straw hat pirates looking for the entrance of Wano to fulfill the promise of freeing up his friend Kinemon and Momonosuke's homeland and people from a Yonko ( an Emperor of the Sea ) Kido's reign that they made of before.
Realizing the entrance to wano being a challenge in itself with its steep falls and mysterious entrance, despite all their efforts they end up getting their ship stuck in a vortex only to find out that they all have entered Wano but have gotten separated to each other in the storm.
With now luffy finding himself almost on the other end of Wano with their ship “The Sunny” there seems to be a disconnect between the straw hat's whereabouts in the very beginning of the Wano arc which Oda Sensei cleverly addresses, depicts and fixes by ensuring viewers that all the crew members have found different disguises and are working towards their plans and getting together with their teammates soon enough as fellow citizens of the country of Wano.
The only condition for them now in order to successfully execute all of their plans was that they lay low without causing any commotion for anyone in Wano but as always it wasn’t Luffy’s style to do anything without causing the loudest stir ever which he does by directly picking a fight with the Ruler of Wano i.e. Yonko Kaido himself when all the straw-hats after getting united somehow again along with the Law Pirates wanted the least for Luffy to do.
The fight was over almost as soon as it broke out between Luffy and Kaido with the result being obvious enough i.e. Luffy miserably losing to the Yonko stating the humongous difference between the strengths between the two with the Yonko proving it to everyone once again how overwhelmingly powerful he is.
With now luffy being captured by Kaido after losing and ending up in the Wano prison along with other notorious folks like the captain of the Kid Pirates i.e. Eustass Kid and his comarade Killer, along with a few others who all have been kept caged there.