Urashima Taro is based on a well-known Japanese folk tale about an honest fisherman who is invited to an underwater castle after saving a sea turtle on a beach from bullies.

Based on its content and the circumstances prevailing at the time of its discovery, [this] film was presumed to be a work produced by Kitayama at the film studio of Nippon Katsudo Shashin Corporation (Nikkatsu) in 1918. Recently, however, stills from the film Urashima Taro released by Nikkatsu in 1918 have been discovered in a magazine. These stills do not appear in [this] film, so we are led to believe that this film is not the work produced by Kitayama at the Nikkatsu studio.

(Source: Japanese Animated Film Classics, forum.bcdb.com)