http://en.wikipedia.org/wiki/Xu_Fu
Xu Fu (Chinese: 徐福 or 徐巿, not to be confused with another Chinese character 市, the pronunciation of which is Shi), was born in 255 BC in the Qi and served as a court sorcerer in Qin Dynasty China when he was alive. During his lifetime, he was sent by Qin Shi Huang to the eastern seas twice to look for the elixir of life. His two journeys occurred between 219 BC and 210 BC. It was believed that the fleet included 60 barques and around 5000 crew members, 3000 virgin boys and girls, and craftsmen of different fields. After he embarked on his mission again in 210 BC, he never returned. Various records shows that he arrived and died in Japan.
Voyage
The ruler of Qin, Qin Shi Huang feared death and sought a way to live forever. He tasked Xu Fu with finding the secret to immortality. In 219 BC, Xu Fu was sent with three thousand virgin boys and girls to retrieve the elixir of life from the immortals that lived on the Penglai Mountain in the sea to the east. Xu sailed for several years without finding the mountain. In 210 BC, when Qin Shi Huang questioned him, Xu Fu claims there was a giant sea creature blocking the path, and asked for archers to kill the creature. Qin Shi Huang agreed, and sent archers to kill a giant fish. Xu then set sail again, but he never returned from this trip. The Records of the Grand Historian says he came to a place with "flat plains and wide swamps" (平原廣澤, possibly Kyūshū of Japan) and proclaimed himself to be king, never to return.
Later historical texts were also unclear with where Xu Fu actually ended up. Sanguo Zhi, Book of Later Han, and Guadi Zhi all state that he landed in "Zhizhou" (直洲), but the whereabouts of Zhizhou are unknown. Finally in the Later Zhou Dynasty of the Five Dynasties and Ten Kingdoms Period, monk Yichu clearly wrote that Xu Fu landed in Japan, and also said Xu Fu named Mount Fuji as Penglai. This theory is echoed by the "Legend of Xu Fu", well known in Japan as evidenced by the many memorials of him there.
Legacy
Xu's arriving in Japan evoked the development of ancient Japanese society. The Jōmon culture which had existed in ancient Japan for over 6000 years suddenly lost trace around 300 BC. The farming techniques and iatrical knowledge Xu brought along improved the life quality of ancient Japanese people. He also introduced many new plants and techniques to ancient Japan. As a result, Xu was well respected among Japanese people and was worshiped as the "God of farming", "God of medicine" and "God of silk". Numerous temples and memorials of Xu could be found in many places in Japan.