Known for its subtle, semi-aromatic character and, increasingly, its versatility, Koshu has been gaining attention in Western markets with limited but growing distribution in the UK and US.
From the classic crisp and ethereal style to more textured ‘sur lie’ expressions, the pink-skinned grape is now used to produce a wide range of wines, including sparkling and orange.
The best examples are earning top awards at international competitions. The most recent was the 2024 Decanter World Wine Awards, where Suntory’s Tomi Koshu 2022 became the first Japanese wine to achieve the top accolade – Best in Show. Koshu Misawa Vineyard, the flagship cuvée from boutique family producer Grace Wine, was also among Decanter’s top-scoring wines last year.
Scroll down to see 13 Koshu wines to try
Read on to explore the history of Koshu and discover 13 Koshu wines worth seeking out, recently tasted at the annual Koshu of Japan event in London.
Tomi-No-Oka’s Koshu vineyard with Mt Fuji in the background. Credit: KoshuofJapan.com
Yamanashi, home of Koshu
Koshu is a native Japanese grape variety that has been grown domestically for centuries, but has only been used for winemaking since 1874. It was considered to have originally come from China via the Silk Road, according to the domestic trade organisation, Koshu of Japan.
The name ‘Koshu (甲州)’ comes from the ancient kingdom of ‘Kai (甲斐)’, which is located in the area now known as the Yamanashi prefecture. It now covers 480 hectares (ha) of vineyards in Japan, with 95% grown in the Yamanashi prefecture, in the shadow of Mount Fuji.
According to local legend, there are two tales about how the Koshu grape was discovered.
The first is that during the Nara period (AD 710-784), a well-respected monk named Gyōki had a dream of Bhaisajyaguru (the Buddha of healing and medicine), who was holding a bunch of grapes. Gyōki made a wooden sculpture depicting what he saw and on his way to deliver the sculpture to Daizenji Temple in Katsunuma town, he discovered a grape vine. Assuming this was a divine gift, Gyōki used it for medicinal purposes.
The other version of the story is less mysterious. In 1186, a Katsunuma villager named Kageyu found an unusual species of wild grape on his way back from a religious ritual. He took the seeds and planted them in his own farmland. Five years later, the vine finally started to produce purple-red fruit. Legend has it that Kageyu presented the Koshu grape to Minamoto no Yoritomo, the first Shōgun of the Kamakura government.
Koshu was seen as a table grape for centuries, until 1870, when a monk and a businessman joined forces to start making wine in a temple. They decided to give winemaking a try as they had seen Westerners drinking grape wine in Yokohama, then a major port and base of foreign trade in Japan.
Inspired by the soybean press used for making miso paste, they brought in their own wooden hand press, as well as large sake barrels to store their wines.
In 1877, Katsunuma established its own winemaking company literally named ‘the Great Japanese Wine (大日本葡萄酒会社)’, and sent two young pioneers, Takano Masanari (高野正誠) and Tsuchiya Ryuken (土屋龍憲), to study viticulture and oenology in France. This move marked the dawn of modern winemaking in Japan, as recorded by the official textbook of Japan Sommelier Association.
Koshu grapes trained on the traditional pergola system, sheltered under plastic rain cover. Credit: Koshu of Japan
Viticulture
In 2004, UC Davis conducted DNA research on Koshu and confirmed its status as vitis vinifera. It is believed to have travelled from Europe via the Silk Road to China and then to Japan.
The vast majority of Koshu grapes are produced in Yamanashi – Japan’s ‘Home of Fruits’ at the foothills of Mount Fuji – which features volcanic soils with clay, gravel and silt.
In his 2023 Expert’s Choice, Hayato Kojima reported a production of 3,300 tonnes in the region in 2018, based on figures provided by Japan’s national tax agency – although not all of the production is used for winemaking.
According to the prefecture’s official site, the region had 400ha of Koshu grapes planted by 2015.
Being a major fruit-producing region in Japan for over 1,000 years, Yamanashi is one of the driest regions in the nation. Even so, the average rainfall in Katsunuma town can reach over 1,000mm per year, with nearly 80% of that falling during the growing season.
Sufficient rain, combined with a high-vigour grape variety, makes yield control difficult for growers.
Traditionally, both issues are addressed by training the vines high above the ground on an X-shaped pergola system, with long cordon pruning applied as a more recent, easier-to-manage alternative. Pioneering producers such as Grace Wine and Suntory’s Tomi no Oka Winery are also trialling a vertical shoot positioning (VSP) system, and are already achieving impressive results.
Although Koshu grapes have thick skins, to better protect them from continuous rain, traditionally growers adorn individual bunches with ‘hats’ (mostly made from wax paper), showcasing an incredible display of attention to detail. Modern methods such as overarching plastic rain covers are also used as a less labour-intensive way to keep these pinkish bunches dry and healthy.
Protective ‘rain hats’ on Koshu bunches. Credit: KoshuofJapan.com
Flavour profile
For much of its history, Koshu was crafted as a sweet and fruity wine – until the 1980s, when local producers began exploring drier expressions and ‘sur lie’ styles.
A delicate, semi-aromatic grape, Koshu typically lends itself to refreshing still and sparkling wines with subtle notes of yuzu, kabosu (Japanese lime), pear blossom and steamed rice. Its bright yet unobtrusive acidity lends a sense of purity and finesse.
When aged on the lees or in used barrels, Koshu gains body, texture, more umami depth and even a gentle grip. Extended skin contact reveals more red fruit characteristics, often taking on an orange hue.
Winemakers tend to eschew excessive new oak, allowing the grape’s pristine, understated elegance to shine.
With its elegant profile, Koshu is a natural companion to seafood and the more subtle, umami-rich Japanese dishes – with sushi and tempura among the top options.
