One Piece Chapter 8.3, page 18-19: Nami Enters

One of the large, stitched-faced pirates confronts Luffy, saying, "AM I RIGHT? BOSS! THAT MAP WAS CAPTAIN BUGGY'S TREASURE!!" He swings his sword, slashing the top of Luffy's straw hat. Luffy gasps in shock as his hat is damaged. Enraged, Luffy delivers a powerful punch that sends the pirate flying backward into his comrades, knocking them all down. Luffy catches his falling straw hat, his face turning serious and angry as he warns, "DON'T YOU DARE... MESS UP MY HAT!!

The remaining pirates groan in pain on the ground, defeated. Watching from a nearby roof, Nami is amazed and exclaims, "WOW! YOU'RE REALLY STRONG! YOU BEAT THOSE GUYS WITH SWORDS BARE-HANDED!" Luffy looks up at her, confused, and asks, "AH? WHO ARE YOU ANYWAYS?" Nami jumps down and introduces herself with a confident smile: "I AM A THIEF WHO ONLY STEALS TREASURE FROM PIRATES! MY NAME IS NAMI. WANT TO BE PARTNERS?" Luffy looks at her, repeating, "ONLY STEAL TREASURE FROM PIRATES?