Domaine KOSEI
ドメーヌ コーセイ
Japan's most focused Merlot specialist — former Chateau Mercian chief winemaker Kosei Ajimura's lifetime pursuit of Kikyogahara Merlot, bottled without filtration or fining.
Domaine KOSEI is a single-varietal Merlot winery established by Kosei Ajimura in the Kataoka district of Shiojiri City, Nagano Prefecture, within the Kikyogahara Wine Valley. Ajimura, born in 1957 in Iwakuni, Yamaguchi, graduated from Yamanashi University Graduate School in 1983 and joined Mercian (then Sanraku Ocean). After studying at the University of Bordeaux in France, he served for many years as the chief winemaker at the Katsunuma Winery where he also co-developed the acclaimed "Chateau Mercian Kikyogahara Merlot". Upon early retirement, he established Domaine KOSEI, began grape cultivation in 2016, and completed the winery in 2019. The winery cultivates only Merlot in the Kataoka district at approximately 700 meters altitude, in well-drained, moisture-retaining soil on former mulberry fields. All wines are bottled without fining, cold stabilisation, filtration, or heat treatment. The vineyards are planted with roses at their borders — roses being more susceptible to disease than vines, they serve as an early warning system for vineyard health. The inaugural red wine, "Kataoka Merlot 2019", received the Grand Gold at the Bordeaux Wine Challenge, validating Ajimura's pursuit of world-class Merlot in Shiojiri.
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Who Is This For?
Wine lovers who want to discover the world-class potential of Japanese Merlot — and anyone who believes a winemaker's life work can be poured into a single glass.
Frequently Asked Questions
- Why does Domaine KOSEI focus exclusively on Merlot?
- Founder Kosei Ajimura spent decades perfecting Kikyogahara Merlot at Chateau Mercian and believes the Kataoka district's volcanic-origin soil and 700-meter altitude produce a distinctive Japanese expression of Merlot. Rather than diversifying, he chose to devote his second career to mastering one grape in one place.
- What does 'unfiltered' mean for Domaine KOSEI wines?
- All Domaine KOSEI wines are bottled without fining agents, cold stabilisation, filtration, or heat treatment. This preserves the full texture and aromatic complexity of the Merlot grapes but means the wine may show a natural sediment — a sign of minimal intervention rather than a defect.
- What awards has Domaine KOSEI received?
- The inaugural red wine 'Kataoka Merlot 2019' won the Grand Gold (highest gold) at the Bordeaux Wine Challenge — a significant achievement for a new Japanese winery and recognition from the heartland of Merlot itself. The winery has also received recognition at the Japan Winery Award (JWA).