Urashima Taro is the protagonist of a Japanese fairy-tale about a fisherman who rescues a turtle and is rewarded for this with a visit to the Ryugujo (Dragon Palace) under the sea. He stays there for three days and, upon his return to his village, finds himself 300 years in the future.
One day a young fisherman named Urashima Taro rescues a turtle on the beach that was being tortured by a group of children. He is then invited by the grateful turtle to an underwater palace of Dragon, where he is entertained by the princess Otohime.
Taro stays there with Otohime for a few days, but soon wants to go back to his village and see his aging mother, so he requests permission to leave. The princess sends him off with parting gift, a mysterious box called tamatebako which he is told never to open.
When Taro returns to his hometown, everything has changed. His home is gone, his mother has vanished, and the people he knew are nowhere to be seen. He asks if anybody knows a man called Urashima Taro. They answer that they had heard someone of that name had vanished at sea long ago. He discovers that 300 years have passed since the day he left for the bottom of the sea. Struck by grief, he absent-mindedly opens the box the princess had given him, from which bursts forth a cloud of white smoke. He is suddenly aged, his beard long and white, and his back bent.