Urashima Tarou (浦島太郎 Urashima Tarō) is a Japanese legend about a fisherman who rescues a turtle and is invited into the Dragon Palace.
One day, a fisherman named Urashima Tarou saw a group of children bullying a turtle. He helped the turtle and released it back into the sea. The turtle took him to the Dragon Palace under the sea. There, he met the Princess of the Palace. The Princess welcomed him and allowed him to stay in the palace. Urashima Tarou stayed for a few days but was soon worried about his aging parents, so he requested permission to leave. The Princess gave her permission and presented a treasure box to Urashima Tarou, but warned him never to open it.
Urashima Tarou returned to the seashore by riding the same turtle that took him to the palace, but cannot find his house or his village. After asking around, people told him that they did heard of a man named Urashima Tarou that disappeared into the sea a long time ago. Urashima Tarou discovered that although he only spent a few days in the Dragon Palace, several thousand years had passed on the surface. Stuck by grief and had no where else to go, he opened the box given by the Princess. A cloud of white smoke raised from the box and turned him into an old man. Apparently, the box was holding his "years", preventing him from aging.