The Mysterious Curse of the Haunted Castle

is episode 194 of the original Naruto anime.

Synopsis
When the daimyō's wife, princess Kayo of the Land of Honey went missing, Naruto was sent on a mission to find her with Hinata and Kiba. Upon arriving at the princess' last known location, they found a large castle and decided to investigate, much to Naruto's disapproval due to his fear of the supernatural. Soon after entering, the team began finding all kinds of strange things happening like people in pictures moving and books flying. Soon it became clear that the castle was not what it appears. It was later discovered that fifty years ago the ruler of the castle, Kōza Kubisaki, placed a "curse" on the castle so all who entered it would be devoured. Hinata then used her Byakugan to discover that the castle was somehow alive.

After discovering this, the castle appearance changed to what appeared to be the insides of a giant creature. They were able to discover that the creature was actually a giant chameleon summon that had been carrying out its dead master's orders for over fifty years. Through the surprising help of the spirit of Kōza they were able to find the summon's summoning scroll and destroy it, causing the summoning to disappear. Naruto and his team were barely able to escape with Princess Kayo and her men. Afterwards, Naruto and his team surmised that Kōza simply wanted their help to finally let the summoning go home.

Trivia

 * In the English dubbed version, when Naruto trips over one of the dead samurai, he yells out "Zoinks!". This is a familiar yell of Shaggy, from the Scooby-Doo cartoon series that deals with many supernatural mysteries. The episode itself is very similar to the series in many aspects.