One Piece Chapter 5, page 13-14: CHAPTER 5: THE KING OF THE PIRATES AND THE MASTER SWORDSMAN

Zoro continues to lecture Kuina, shouting, "SOMEDAY I'LL BEAT YOU BECAUSE I WORKED HARD, NOT BECAUSE YOU GOT WEAKER!! IT'S GOT NOTHING TO DO WITH BEING A BOY OR A GIRL!! I'M TRAINING ALL THE TIME TO BEAT YOU! YOU'RE MAKING ME LOOK BAD!" Kuina listens quietly. Zoro then proposes, "LET'S MAKE A PROMISE TO EACH OTHER! SOMEDAY, ONE OF US WILL BECOME THE GREATEST SWORDSMAN EVER!! WE'LL FIGHT EACH OTHER FOR THE TITLE!" Kuina, crying tears of joy, smiles and calls him a "YOU IDIOT! YOU'RE TOO PUNY!" Zoro firmly declares, "IT'S A PROMISE!" as they seal their pact.

The next day, a dojo student runs up to Zoro with tragic news: "ZOLO! THERE'S BEEN AN ACCIDENT! IT'S KUINA! SHE FELL DOWN THE STAIRS... SHE'S DEAD!!!" Zoro is completely devastated. At her funeral, Zoro stands before her covered body, crying as Koushirou tells him, "HUMANS ARE FRAGILE THINGS, ZOLO..." Zoro begs his master, "SENSEI! MAY I HAVE HER SWORD?" Koushirou replies, "...I SUPPOSE SO..." Zoro holds the sword tightly, weeping and screaming, "I'LL HAVE TO KEEP THE PROMISE FOR BOTH OF US. I'M GOING TO BECOME SUCH A GREAT MASTER SWORDSMAN THAT MY NAME WILL BE KNOWN EVEN IN HEAVEN!!!!