 The episodes story is loosely based on the Japanese folk tale of  Urushima Taro. In short: Urushima Taro, a fisherman, saves a turtle  from being killed. The turtle takes him off to an undersea palace  where he is feasted and entertained until he has had his fill. When  he leaves, he is given an ornate box and a warning to never open it.  He returns home to discover that decades have passed, yet he hasnt  aged. Finally, curiosity is too much for Urushima Taro, who opens  the box, to find that it contains his old age.