Yamanashi prefecture is in the central part (Chubu) of the Honshu island of Japan. It is bordered on the south and west by Shizuoka prefecture, on the west and north by Nagano prefecture, and on the east by Saitama, Tokyo, and Kanagawa prefectures. Thus, it is landlocked.
In terms of both population and area, Yamanashi is a fairly small prefecture. There are no really major cities in Yamanashi prefecture, though Kofu and Minobu are worth mentioning. 78% of the prefecture is forests and mountains.
Historically, this area was called Kai no kuni, or Kai country. In the 12th century, Minamoto Kiyomitsu, the son of Minamoto Yoshikiyo, moved to Kai and started the kaigenji, or "Kai Minamoto." The most successful family of the kaigenji was the Takeda sub-family, the most successful of which was the daimyo, Takeda Shingen. After Shingen's death in 1582, the area came under the control of Oda Nobunaga, Toyotomi Hideyoshi, and Tokugawa Ieyasu. Later, in 1724, the area came under the direct control of the Edo bakufu.
In 1868, the Meiji government took Kofu Castle and formed the area into Kai Prefecture. On November 20, 1872, the prefecture was renamed Yamanashi. In the late Meiji period, the Chuo railway line from Tokyo came to Kofu and brought with it some measure of industrialization. However, much of the prefecture's transportation was done via the Fuji River until 1926, when the Minobu railway line opened, linking Kofu to Shizuoka city and, thus, to the ocean.
The scenery of Yamanashi prefecture is spectacular and this is what it is primarily known for. The Chichibu mountain range and the Southern Alps both host peaks over 3000 meters, and the forests are electrifying in the fall. Yamanashi prefecture is also famous for its hot springs or onsen and its grapes. It is Japan's primary wine-making region, and the grape harvest is another big tourist draw in the fall. The Fuji Five Lakes are also located in this prefecture.
Source: http://www.pref.yamanashi.jp/