In the "One Piece" series, Roronoa Zoro acquires his cursed sword, Sandai Kitetsu, during the storyline set in the East Blue arc. Zoro obtains the sword in the Loguetown arc, specifically in Chapter 97 of the manga and Episode 48 of the anime.

After the death of Kuina, Zoro's childhood friend and fellow swordswoman, he travels to Loguetown. There, he encounters a swordsmith named Tenguyama Hitetsu, who presents him with three swords to choose from. Zoro selects Sandai Kitetsu as his new sword.

Sandai Kitetsu is known to be a cursed sword, and it is said that those who wield it are destined to encounter misfortune and tragedy. However, Zoro is undeterred by the curse and accepts the challenge of mastering the sword despite its reputation.

Since obtaining Sandai Kitetsu, Zoro has showcased his remarkable skill and strength with the cursed sword, incorporating it into his fighting style as he continues his journey to become the world's greatest swordsman.