Those who reside in Tokyo will know that any excuse to leave behind the oppressive heat and humidity of the city in late July will do. Venture down deep into the lowest tunnels of Ueno Station and on to the air-conditioned Toki Express — perhaps throw in a late-connecting train and a ticket mix-up to add a dash of excitement to the building anticipation — and apart from the inertia pulling you back into your seat as the bullet-train gets underway, you hardly sense any movement. It is only by looking through the window and seeing the blurred landscape zipping by that you really have an inkling this particular beast has a top speed of 275kph.

The Joetsu Shinkansen line heads north north-west from the world’s largest metropolis, traversing the country through tunnels, rice paddies, forests and towns to terminate in the City of Niigata on the coast of the Sea of Japan. Completed in 1982, our Toki Express covers the 269.5 kilometres in just under 110 minutes. It takes less than an hour to get to Jōmō-Kōgen Station in Gunma Prefecture. Nagai Shuzō in the village of Kawaba, today’s destination and an excuse to get out of Tokyo at even the best of times, is another twenty-five minutes away by hired van.

Founded in 1886 by Nagai Shoji, a high-ranking samurai who crossed from a neighbouring prefecture and chose to take the family in a new direction, the brewery makes Mizubasho sake, one of Japan’s most respected brands. Although they produce many styles, Nagai Shuzō is perhaps best known as pioneers of Awa Sake, which I’d say is the pinnacle of sparkling sake. Unlike many other products that have gas added to the still product, Awa sake fermentation is completed in the bottle, trapping the naturally occurring CO2 in a similar way gas is captured in champagne. The patented process leads to a much more complex and interesting beverage.

To the river

We meet Nagai Noriyoshi and his wine expert wife Matsumi at the door then jump straight back in the van. Five minutes in the country is very different from how a city dweller measures time. What sounded like a comfortable walk through the rice paddies becomes a drive along a serpentine road up into the Tanigawadake Mountains, with said paddies morphing into tightly packed trunks of Japanese cedar. This forest is not only home to bears, deer and wild boar; here you’ll also find some of the purest water in Japan.

We pull over to the side of the thin road and make our way down a short wooden staircase to a boisterous stream trying to insist it will soon become the Tone River. There are no houses or cultivation in the mountains above this point, which is important in maintaining the purity of the water. It probably goes without saying, but the quality of the supply is critical in the production of any high-end beverage requiring water, especially one as water-intensive as sake production.

To protect the area and preserve the environment, Nagai Shuzō has been purchasing more of the surrounding forest. Nagai san points at two painfully thin trunks standing within centimetres of each other, dwarfed by the Japanese Cedar around them but still reaching three-odd metres towards the sky, another indicator of how untouched this area is. “How old do you think they are?” With their height exacerbating their slender trunks it feels as if you could easily push them over. I guess five years. “Fifteen years” he replies.

Fifteen years and I can almost loop the trunk with my thumb and forefinger. That’s incredibly slow growth. If it takes this long to get to this point, I can only wonder how long some of the towering cedar around us have been pushing towards the sky. As we drink water scooped directly from the stream behind us, Nagai san explains his vision that led to the creation of Awa Sake.

Always wanting to produce sake that would be accepted around the entire world, it was on a trip to the Champagne region in France where things clicked for him. Seeing growers pouring their hearts into the production, and wineries with hundreds of years of history, he knew the direction in which he wanted to take the brewery. He decided to introduce sake in a different way, totally removed from people’s expectations as they were at the time.

Exploding bottles

Pressure is measured in metric ‘bar’ units, which, for most intents and purposes, represents the pressure of the atmosphere at sea-level. The gas inside some sparkling drinks brings the internal pressure to around 2.5 bars, or (effectively) two and a half times the air pressure at sea-level. Champagne is bottled at much higher pressure — 5 to 6.2 bars. To draw a flawed analogue that adds perspective, the tyres on the average passenger car are in the 2.2 to 2.7 bar range when they’re cold. The pressure in a bottle of champagne is more like the pressure in the tyres of a double-decker bus, which helps to explain why the glass of champagne bottles are so much thicker than those of still wine.

Nagai san fetches the bottle Mizubasho Pure sparkling sake from the ice. At over 5.5 bar, Awa comes in at a similar pressure to champagne, as evidenced by the respect he displays as he opens the bottle, and the noticeable pop heard over the sound of the gurgling water. That kind of pressure must have created some interesting challenges in developing the concept. “How many bottles did you lose?” I ask as he pours. “How many exploded in the development phase?”

Nagai san grins, perhaps with a hint of pride blended with a touch of chagrin. “About 3000,” he replies, to our shocked laughter. “What? Really? That’s amazing dedication.”

“Hmmm” he continues, “I had quite a few sake showers on the way.” The wide smile suggests he thinks it was all worth it. One sip and you’d have to agree.

Mizubasho Pure Awa Sake

Tasting reveals a touch of yogurt, with a hint of sweetness that fades to dry on the finish. Fine bubbles married to elegance, you’d be hard pressed to find a better way to have a toast or start a meal. For this reason, and a realisation of Nagai san’s original dream, in Japanese embassies around the world you’re now likely to be offered a glass of Pure Awa Sake when you might be expecting sparkling wine.

Mizubasho 2018

Made with the extremely rare Yukihotaka rice, the year-stamped Awa Sake is all about honey and caramel. There is a similar sweetness to Pure, and a certain creaminess and depth that cannot be denied. The flavours linger on the palate. This bottle will not be so easy to find, but I’m sure you won’t be disappointed should you track it down.

Neither Pure nor the 2018 has the bracing acidity you would expect from the world’s most famous sparkling wine offerings, an acidity that doesn’t always work with some traditional Japanese dishes like sashimi. Having said that, there is definitely enough sharpness that either of these outstanding sake will match with a variety of cuisines, both Japanese and non-Japanese. Food aside, I am absolutely certain Awa Sake will match excellently with sunset on a beach, or a lazy afternoon with a novel on a balcony, just as well it pairs so perfectly with standing on the banks of a boisterous stream trying to insist it will soon become a river in a Japanese mountain forest.