There aren’t many wine styles that are unfamiliar to most people in the booze trade, but Japanese Koshu is surely one of them. I don’t mind admitting that before the recent KOJ (Koshu of Japan) tasting in London, my knowledge of the country’s signature wine style was next to non-existent. I was more familiar with Korean Gamay than Koshu.

I’m not alone in this, apparently. Even in Japan, relatively little is known about Koshu. And those who have tasted it are prone to dismiss it. One Japanese wine writer, keen to replicate the views of Andy Gray and Richard Keys perhaps, reckons that Koshu is “like Japanese women. It has no character.”

How to remedy this state of affairs? KOJ had the smart idea of inviting Jancis Robinson MW to present a master class of nine wines before tasters were let loose on the samples upstairs. Her comments were typically erudite and concise, based on three visits to Japan. Koshu, she told us, is “quite unlike anything I’ve ever tasted before”. It was getting more intriguing by the minute.

The basic lowdown on Koshu is as follows: it is Vitis vinifera (or at least 98% of its genes are) and probably came to Japan along the silk route. It has thick, pinkish skins, is potentially very vigorous and prone to coulure in the vineyard. Most of the 80-odd producers are small (I’m not talking physical stature here), which means that with few exceptions (Suntory and Mercian) economies of scale are rare. The majority of the vineyards are in Yamanashi, the area of Mount Fuji, and are grown on pergolas.

And its character, or lack thereof? Even Jancis conceded that it is “one of the most neutral grapes” but argued that such neutrality can be an advantage when the wine is paired with sushi and sashimi. After all, she added, raw white fish can be comparatively neutral too. “I like the zen purity of Koshu,” she said. “It’s low key, calming and pure. There’s a great correlation with the Japanese character.”

Tasting the wines from KOJ’s members, I could see what she meant. To some, we are in white spot on a white wall territory — the bland leading the bland, as it were — but there are definitely subtle differences between them, based on yield, soil type, picking dates, phenolics, residual sugar, lees contact and (occasionally) barrel fermentation. Quality, too, varies considerably. My favourites were from Grace, Soryu, Rubaiyat, Haramo, L’Orient, Lumière, Mars Wine and Suntory.

Where does Koshu sit in the world of wine? Inevitably, it is often compared with other neutral grapes. Chasselas was mentioned, as were Melon de Bourgogne (the variety used to make Muscadet) and Aligoté, but to me the better examples have elements of unoaked Chablis, Albariño and even Loire Sauvignon Blanc about them. It is no coincidence that Denis Dubourdieu, the French oenology professor who specialises in the last variety, consults for Mercian.

The more immediate question is whether there is a market for Koshu in the UK. Prices are steep (I couldn’t find anything below £16 retail), which makes the wines something of a hand sell. They are best suited to restaurants, possibly as a by-the-glass pour, and with Japanese food. It would help if the wines were bottled under screwcap (very few are at present) as their flavours are so delicate that the slightest hint of cork taint or oxidation can ruin them. They could also do with a few more stockists. Selfridges list a couple, as do Novum, while Ellis of Richmond and Enotria are looking at the category, but that’s about it.

Now is surely a good time to be promoting Koshu. Is it just me, or is there a strong move away from over-ripe, over-alcoholic, over-oaked blockbusters towards subtler wines? Some of the more prominent American wine critics may be stuck in the 1990s, when bigger was almost always better, but they look increasingly out of step with public taste. Marks & Spencer, among other UK retailers, is focusing on lighter, food-friendly wines, promising to list more than 100 examples under 11% by April.

Koshu, like other subtle, unoaked white wines, makes demands on us as tasters. Rather than being blown away by gobs of fruit, oak and alcohol, we are required to examine nuance and complexity. The wines whisper in your ear, rather than shouting at you, but that’s not necessarily a bad thing. The differences are there; they’re just hidden below the surface.

I can’t imagine that the buyers from Tesco and Sainsbury’s are considering a Finest or Taste the Difference Koshu in the near future, but this isn’t a mass market product. It’s too niche and expensive for a start. But I really enjoyed my first taste of Koshu. I’m still no expert, but it was great to experience one of the world’s least known wine styles. Next time I’ll drink Koshu with Japanese food.

Originally published in OLN