The Imperial Sword Killing the Devil (1981)

Five men venture into a hidden cave to find a treasure map. After they have encountered the dangers of the cave (body melting acid, a flying mini-dragon, living skeletons...), the two last survivors finally find the treasure map inside a golden Buddha. One of them falls into a pit and the other gets caught by ninjas as he tries to escape with the map while the cave explodes. After escaping from the ninjas, he meets a princess to learn the imperial sword technique in order to defeat the devil!