One Piece Chapter 6, page 3-5: Chapter 6: Number One

With a massive, resounding "KLANG!", Zoro blocks the onslaught of the Marine execution squad. Having successfully retrieved his three swords, he holds one firmly in his mouth and one in each hand, effortlessly halting every single blade aimed at him and Luffy. The impact creates a powerful shockwave, leaving the Marines completely frozen in place.

Captain Morgan and Koby stare in absolute shock, with Morgan uttering, "RORONOA ZOLO!!!" and Koby gasping, "...!!" Luffy, on the other hand, is completely thrilled, cheering, "WOW!! HE'S COOL!!" Zoro, holding his three swords in a deadly stance, stares down the execution squad with intense, cold eyes. He warns them, "THE FIRST ONE WHO MOVES... DIES." Terrified by his overwhelming aura, the Marines tremble and back away, whimpering, "EEEEK...!" and "HE'S SO SCARY...!

Zoro addresses Luffy while keeping his swords ready, saying, "ALL RIGHT, SO I'M A PIRATE. I GAVE YOU MY WORD. I'VE FOUGHT THE NAVY, THEREFORE I'M OFFICIALLY AN OUTLAW... BUT, HEAR THIS!! I HAVE A MISSION TO FULFILL!!!" He looks directly at Luffy with fierce determination and declares, "I'M GOING TO BE THE WORLD'S GREATEST SWORDSMAN! ALL I HAVE LEFT IS MY DESTINY! MY NAME MAY BE INFAMOUS... BUT IT'S GONNA SHAKE THE WORLD!!!" He then adds a stern warning: "BUT YOU ARE MAKING ME BECOME A PIRATE! SO IF I HAVE TO ABANDON MY DREAM FOR ANY REASON......THEN I'M GOING TO MAKE YOU COMMIT HARA KIRI!!!