On a hot summer’s day in southwest France, Courvoisier master blender Thibaut Hontanx steps into the cool of a 200-year-old warehouse, whose doors open onto the somnolent Charente river. The cellar, Chai Renard, named afterthe maître de chai between 1909 and 1938, Louis Renard, is the high point of the visit for anyone who takes a tour of the Courvoisier maison in Jarnac.

It houses some special vessels. There are casks containing eaux-de-vie from the different terroirs of the region; dames-jeannes of decades-old cognacs, which have reached their peak and are preserved in glass; and a complete collection of historical bottles of the famous Napoleon brandy (including a bottle from the late 1960s, as mentioned in the song Where Do You Go to My Lovely). And there, sitting alone, is one cask with “Mizunara Cognac” etched on it.

‘In 2015,’ says Hontanx, ‘about a year after Suntory bought Beam Inc., the president of the company visited Jarnac and asked my predecessor as master blender, Patrice Pinet, if there was anything he could do for him. And Patrice told him he would love to try ageing cognac in mizunara. The president went back to Japan and said, “Send him one mizunara barrel”.’

This may seem stingy, but, actually, it was pretty generous, given the context. No cognac had ever been aged in this unique wood (a French brandy was rushed out before Courvoisier’s Mizunara). Mizunara is a rare sub-species of oak which grows very slowly, at altitude. In fact, it takes 200 years to reach maturity and forests containing these trees have to be managed sustainably, as Beam Suntory does in the forests it owns. Another limiting factor is that it twists as it grows and the grains can be very porous, so few mizunara oaks are viable for coopering. Originally, mizunara was only used by the Japanese whisky industry as a last resort because of the Second World War blockade meaning whisky casks could not be imported.

Although scarce and hard to work with, casks that successfully held liquid imparted unique coconut and spice notes. This was a factor in the growing reputation of Japanese whisky. More recently, “mizunara finish” became a buzz phrase in Irish whiskey and Scotch. Demand outstrips supply – the number of new casks coopered annually is in the hundreds, not the thousands – to the extent that the cost of each empty cask is around £5,000. An Irish whiskey-maker can buy one that has already been used to age, say, Yamazaki. Not so a cognac-maker – the rules say that they can use any oak to mature their eaux-de-vie, but it can’t have contained any non-grape-based product.

So, Pinet was grateful for that one cask. ‘What was great about it was the exchange he had with Shinji Fukuyo, the House of Suntory master blender, sharing their passion for oak maturation. I joined Courvoisier in 2021 just as the first Mizunara was being finalised, so I had the chance to work with the two of them and learn what they’d done to create it. One of the things Shinji-san kept saying was that you must be patient with mizunara. Patrice had filled the cask with eaux-de-vie from Grande Champagne that was already XO, but the secondary maturation took 40 months, more than three years, to achieve the right aromas and finesse.’

Even before the first Mizunara was released, it was clear to all concerned that it would work and plans for further Mizunara cognacs were hatched. ‘This time,’ says Hontanx triumphantly, ‘They sent us four casks!’

This was during the period that the two master blenders worked together in the run-up to Pinet’s retirement. If Mizunara mark one was the experiment to see if the secondary maturation would actually work on brandy (using the most elegant of the cognac crus, Grande Champagne), mark two refines it as a more identifiably Courvoisier cognac – the blend uses the three crus found in Courvoisier XO: Grande Champagne, Petite Champagne and Borderies, albeit in slightly different percentages. Hontanx explains, ‘Borderies is known for violet and other floral notes, but as it gets older, it also develops a complex spiciness, which I felt would be complemented by the mizunara.’

Suntory’s Shinji Fukuyo was again involved in the process, mostly as a reassuring voice of calm. ‘After six months, even a year, I have to say I was disappointed: it lacked finesse, was almost harsh. But Shinji said, “Don’t worry. Don’t rush it. Take your time.” And then, eventually, they came – aromas you never have in a cognac, the coconut and sandalwood everyone talks of with mizunara, but tropical fruits too – pineapple and passion fruit.’

The other piece of advice Fukuyo offered was to ensure that Hontanx was happy with the liquid as a cognac more than being a mizunara-led spirit. ‘I think it turned out as he wished; you taste classic cognac notes on the first taste, before the mizunara spices at the end.’

As a collaboration between France and Japan – represented by a little visual gag hidden in the foliage of the gold illustration of a mizunara oak on the bottle – this remarkable cognac meets somewhere between them, perhaps Istanbul’s Grand Bazaar, among the flowers and a mix of spices, there is the aroma of new leather jackets and nut oils.

And in that single original Courvoisier Mizunara cask in Chai Renard, another flavour journey has begun. Hontanx knocks on it knowingly. The high-pitched sound makes it clear it has been refilled, but, as the master blender walks on, he refuses to reveal the blend within…

Only 500 bottles of Courvoisier Mizunara 2023 Edition are available worldwide. In the UK, they are available at Harvey Nichols, Harrods, and Selfridges, RRP £2,500 a bottle.

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