One day, a fisherman named Urashima Taro saves a small turtle from boys who are teasing it. The next day, a turtle comes to thank him by taking him down to the Dragon Palace at the bottom of the sea, where he spends time as if in a dream. But when he returns home, many more years have passed than he had realized. Overcome with sadness, he lifts the lid of a treasure box he was given when he left the Dragon Palace, despite being warned that he should never open it...