One Piece Chapter 1.1, page 23: Romance Dawn (Version 1)

Shiruku screams at the charging pirates, "YOU COWARDS! ATTACKING AN UNARMED OPPONENT!!". Luffy calmly puts a hand on her shoulder, saying, "IT'S FINE, I DON'T USE A WEAPON. STAND BACK FOR A SEC.". Shiruku blinks in confusion, "EH". As the two pirates swing their swords at him, Luffy agilely leaps and dodges their slashes. He flips through the air, landing gracefully on his feet. He looks back at them and says, "YOU GUYS STARTED THIS."