Koshu (甲州 kōshū) is a white wine grape variety that has been grown primarily in Yamanashi Prefecture of Japan. Though long thought to be of exclusively European origin, it is now known to be a hybrid (probably naturally occurring) of Europe's Vitis vinifera and one or more Asian Vitis species. The name “Koshu” is a former name for Yamanashi and the present-day name of the main town in the valley where the majority of Koshu grapes are grown.
The distinctive characteristics of Koshu are a pale straw colour and a soft, fruity and aromatic bouquet with overtones of citrus, peach and honeysuckle. The taste is clean, delicate and fresh, considered a good match for Japanese cuisine.
In the late 19th century, the first proper winery was established in Yamanashi. After the second half of the 20th century, production of Japanese Wine from locally grown grapes increased dramatically. There are now more than 80 wineries in Yamanashi Prefecture; they turn out about 40% of Japan’s domestic wine production, and Yamanashi has 95% of the Koshu plantings in the country.
- “Genetic Analysis of East Asian Grape Cultivars Suggests Hybridization with Wild Vitis”. Nami Goto-Yamamoto, Jason Sawler, Sean Myles, PLOS ONE, October 21, 2015; Koshu Valley website, "Origins of the Koshu Grape"
- "甲州市ワイン振興計画" (PDF). Koshu City. 2019-05-18.
- Koshu of Japan website, page of “Taste” Archived 2013-12-06 at the Wayback Machine; Koshu Valley website, "Koshu Wine"
- Yamanashi Prefecture website, page of “Koshu wine” Koshu Valley website, "History of Japanese Wine Production"