One Piece Chapter 2, page 20: THEY CALL HIM "STRAW HAT LUFFY"

Luffy and Koby sail away in a small boat. Koby is amazed, saying, "YOU MUST HAVE EATEN THE FRUIT OF THE GUM-GUM TREE... INCREDIBLE! BUT LUFFY, IF YOU'RE GOING AFTER ONE PIECE... THAT MEANS YOU'LL HAVE TO ENTER THE 'GRAND LINE.'" Luffy replies, "YEP!" Koby warns, "THEY CALL IT THE PIRATES' GRAVEYARD..." Luffy explains, "THAT'S WHY I'M ASSEMBLING A SUPER CREW. THAT GUY IMPRISONED AT THE NAVY BASE... WHAT'S HIS NAME?" Koby answers, "RORONOA ZOLO!" Luffy smiles, "IF HE'S A GOOD GUY, I'LL LET HIM JOIN MY CREW!" Koby panics, screaming, "NOW YOU'RE TALKING CRAZY AGAIN! NEVER NEVER NEVER! THAT'LL NEVER HAPPEN! THAT GUY'S A DEMONIC BEAST!" Luffy asks, "HOW DO YOU KNOW!?" Koby continues to scream, "NEVER!" A narration box concludes: "AND SO THE TWO YOUNG ADVENTURERS SAIL ON TOWARDS THE NAVAL BASE AND... DESTINY!"