Ever since he was a boy, Zoro Roronoa trained at a dojo in his hometown Shimotsuki in East Blue under the tutelage of a kind and patient instructor, Koshiro. Zoro was the strongest male in the dojo, beating even adults with his Two Sword School technique. However, there was one person that Zoro could never beat regardless of his training and skill, his teacher’s daughter, Kuina. Kuina had beaten Zoro for 2,000 matches even though she used only one sword and Zoro had mastered using two. Even though she was a few years older than Zoro, as he was able to best adults, he did not see that as an excuse for losing to her. For their 2,001st match, Zoro met with Kuina on the night of a full moon and suggested they fight in secret with real swords, rather than the usual bamboo training swords. After the fight began, although he gave his best, in almost no time Zoro suffered his 2,001st defeat. Zoro was furious with himself for losing yet again, but in the privacy of the night, Kuina began to lament that she was the one who should regret the outcome. 

 

Zoro was speechless as Kuina began to cry and explain that as a male who had not yet reached adulthood, in just a few years by virtue of his male physique he would grow stronger than her, as would all male swordsmen and she could never aspire to be the strongest. Instead of gloating over the sudden revelation Zoro became furious with Kuina and told her that thinking like that was nonsense. If she thought of her abilities that way, then if Zoro ever did defeat her she could just use the fact that she was a woman as an excuse for the loss. After all of his hard training and effort, Zoro would have hated her for letting a victory against her be attributed to physiological differences. Kuina took comfort in his words and the two made a special promise that night that one of them would become the strongest swordfighter in the world. 

 

As fate would have it, the very next day Zoro’s training was interrupted by cries from an acquaintance. Kuina had fallen down the stairs at her home and died from the impact. Zoro masked his sadness by being angry with her since they had just made a promise the night before. Although he accused her of running away from him, it couldn’t stop him from being passionate about fulfilling his promise. He begged Koshiro to give him her sword which he allowed Zoro to receive. Zoro made a promise on her sword to become the 'Strongest Swordsman in the World' and from that day on, Zoro trained and battled with three swords.