In the popular anime series One Piece by author and illustrator Eiichiro Oda, Monkey D. Luffy learned to use Haki while training with former pirate king Gol D. Roger's right-hand man Silvers Rayleigh.

Ever since Luffy got a rude awakening in his fight against Kaido, he has been trying to find a way to fight back successfully. But now the time is fast approaching as Luffy kicks off new training for ...

Luffy and Rayleigh say goodbye to Jinbe and go to Rusukaina Island, where Luffy will be trained under Rayleigh. Rayleigh explains to Luffy about Haki, demonstrates for him on a wild giant elephant.

Over the decades, Luffy went from a would-be pirate that could throw a punch or two here and there with his stretchy limbs blessed to him thanks to a Devil Fruit to one of the strongest pirates ...