One Piece Chapter 6, page 14: Chapter 6: Number One

With a ferocious "WHOOOSH!", Captain Morgan swings his massive axe-hand down at Luffy, roaring, "DIE!!" Luffy agilely leaps high into the air, narrowly dodging the lethal strike. The giant blade slices clean through the wooden fence and deep into the ground with a sharp "SLISH...!" sound effect. Watching from a distance, Koby is amazed by the destructive power, exclaiming, "WOW! THAT'S SHARP!!"