One Piece Chapter 5.3, page 11-15: The Pirate King and the Great Swordsman

One night, Zoro challenges Kuina to a duel using real katanas instead of wooden practice swords. Kuina accepts his challenge, and they prepare to fight under the full moon.

Zoro and Kuina clash fiercely in the moonlight. Kuina disarms Zoro, securing her 2001st victory. Zoro falls to the ground in tears, frustrated by his defeat.

Kuina cries and confesses her anxiety about growing up, believing that physical differences will eventually allow boys to surpass her. Zoro angrily rejects her self-doubt, declaring that his goal is to surpass her based on her skill, not her gender.

Zoro proposes a promise: one of them must become the world's greatest swordsman. Kuina tearfully agrees, and they seal their promise with a firm handshake.

The next day, Zoro learns that Kuina died from falling down the stairs. Devastated, Zoro begs Koushirou to give him Kuina's sword, the Wado Ichimonji. Holding the blade, Zoro tearfully vows to become so famous that his name will reach the heavens.