The Cursed Ghost Ship

is episode 225 of the Naruto: Shippūden anime.

Summary
As they continue their voyage towards the Land of Lightning, Naruto, Aoba, Guy and Yamato sail through a thick fog. To pass the time, Yamato tells Aoba and Naruto some ghost stories (much to Naruto's dislike). One of which tells the story of a ship whose crew is comprised entirely of ghosts, which appears in thick fogs such as the one they were sailing through at the time, and can be identified by the flocks of crows that follow it. As Yamato tells the story, a seemingly abandoned ship which meets the exact same characteristics and conditions appears next to their ship. Yamato, Aoba and Naruto board the ship to investigate and Naruto comes across a young boy who says his name is Hishaku. He apparently lived alone on the ship and tended to it but he was once one of the crew of the ship until they were wiped out by a creature Hishaku called the "Skeleton Crab". This creature then attacks the boat, capturing Yamato. Naruto then tells Aoba to warn Guy and the rest of the crew. Naruto, with the help of Hishaku, defeats the Skeleton Crab, and Hishaku then reveals that he is, in fact, a ghost. When the crab attacked the first time, the captain told Hishaku that he was young and to save himself and ever since then, Hishaku's soul couldn't rest, because it felt guilty at letting its crewmates die. When the crab was defeated, Hishaku's soul, and the souls of the rest of the crew members who couldn't rest either, left with the ship, which really was a ghost ship.