Dark Yojimbo

Dark Yojimbo is an optional boss in the international and PAL versions of Final Fantasy X. He can be encountered in the back of the Cavern of the Stolen Fayth. The party must fight him five times to defeat him.

Battle
As any other enemy, he can be killed instantly by Yojimbo's Zanmato attack, but it's extremely hard to get it five times in a row, so a weak party stands little chance against him.