SPOILER WARNING: Details about the Final Fantasy XI in-game storyline follow.
Vukki-Chebukki is actually the legendary bounty-hunter, Goldmane of Tavnazia who, along with Ismenios of Bastok performed great deeds during the Crystal War. He is a native of the Marquisate of Tavnazia, and is said to have lost his wife and children in the war. (His children, the Chebukki siblings, are in fact quite alive: Cherukiki, Makki-Chebukki, Kukki-Chebukki.)
Vukki was once sent on a secret mission by the Tavnazian Cathedral, which later sent an assassin to silence him. Since then, Vukki has opted to live in isolation on a deserted island south of Mhaura.