Why Can the Eight Punches Help Me, Link, Become a Demon?

I know how to use eight punches at the beginning. I was a little angry at first. What kind of ** skill is this? Compared to Luffy's father, Dragon Claw is just a younger brother, right? ! Unexpectedly discovered that the eight punch boxing can be upgraded? Even the legendary pirate Green Pepper has only reached the intermediate level? ! Are you still afraid of a hammer? Since the Eighth Rush Fist is so powerful, how can you become the Pirate King if you reach the full level and add the fruit of the Phantom Beast? ! Reconstruct the pirate world system! The four emperors are just side dishes! I, Link, want to be the big devil! This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.