Japan is blessed with a rich climate and abundant harvests from the sea and mountains. Unlike the cuisines in other countries, which are made tastier by adding more ingredients and layers of flavour, Japan has developed a unique culinary culture that is based on finding the best ingredients and making the most of the flavours inherent in the ingredients themselves. Today, Japanese restaurants mainly use kombu (kelp) and bonito as ingredients for dashi broth, but the technique first appeared during the Muromachi period (1336-1573). The use of plant-based ingredients such as dried shiitake mushrooms, vegetables and kelp, instead of animal broth, in cooking is said to have been influenced by Buddhist teachings. Zen Buddhist vegetarian cuisine, in which dashi was used to add umami to vegetables, has its roots in chakaiseki (tea-ceremony dishes) and kaiseki cuisine (a Japanese banquet meal) enjoyed at traditional Japanese restaurants.

In addition, Japan’s soft water makes it easy to extract umami from kelp, shiitake mushrooms, plants and vegetables, as well as dried bonito flakes, dried sardines, which also contributes to the deliciousness of dashi. Many Japanese restaurants, which place great importance on dashi, are particular about the water they use, selecting high-quality kombu (kelp), freshly shaved bonito flakes with a good aroma, and natural, soft water that brings out the umami flavour of the dashi.

The same is true for Koji Koizumi, owner of the Japanese cuisine restaurant ‘Kohaku’ in Kagurazaka, Tokyo, who took on the challenge of developing éks KAISEKI. “Dashi is the key to cooking. If the dashi is good, it also determines the taste of the dish,” says the chef, who pays close attention to dashi on a daily basis. He says, “We use the synergy of glutamate from kelp, inosinic acid from bonito and natural, ultra-soft water to make dashi broth in order to achieve the peak of deliciousness. In other words, although the dashi broth is rich in aroma and umami, I take into account the temperature, humidity and other climatic factors of the day and fine-tune the temperature of the water, the addition of kelp and bonito, and the timing of straining to avoid any bitterness or other unpleasant tastes.”

Koizumi has studied under Hideki Ishikawa of famed Tokyo Kaiseki cuisine restaurant Kagurazaka Ishikawa since the restaurant was first established and contributed to it gaining three Michelin stars. In 2008, he was appointed head chef at ‘Kohaku’, where he steadily accumulated stars until he was awarded three stars in 2015 at the age of 36. Koizumi aims to, ‘create dishes that can only be found here, dishes that will pleasantly surprise you’, so he incorporates ingredients from outside the confines of Japanese cuisine, such as truffles, caviar and shark’s fin, as well as using his own unique techniques. ‘The aim is not to be pretentious, but rather to move the customers’ hearts by making the deliciousness of seasonal ingredients even more delicious with unprecedented combinations of ingredients and cooking methods,’ he says, adding that although he takes on challenges, his goal is always to create Japanese cuisine. That is why the dashi broth, which determines the flavour, is so important.”

What kind of sake tastes best with Japanese cuisine? “Basically, many customers ask for the sake they prefer, so we try to have a wide range of sake to meet their diverse tastes, from dry to umami, classic and seasonal sake, as well as limited edition sake that is a little hard to find. Although some restaurants collaborate with sake breweries to create their own original sake, ‘I have never wanted to create my own brand because I feel that if I were to create it and recommend it, I would be constraining the tastes and preferences of my customers.”

So why did he decide to get involved in the development of éks KAISEKI? ”Because it will benefit the Japanese cuisine genre as a whole, and it will also be an opportunity for sake breweries to create new value. And for the customers, it will be something they can recommend as the ultimate sake that transcends their personal preferences. It’s a three-way street. We wanted to collaborate in this project so that everyone would be better off.”

And what he envisioned as ‘the ultimate sake that transcends taste preferences’ was, first of all, a well-balanced taste that everyone would find delicious. “It is a sake with a mild aroma, sweetness, acidity, umami and a smooth, well-rounded flavour that is not too spicy or bitter. This balance, in which nothing stands out, is similar to that of a good dashi broth. It is soft on the palate, round and full in the mouth, and harmonises. That’s the image I had in mind.”

“Another important thing is that the sake should have the ability to be enjoyed at any time during the course. In Japanese cuisine, there are raw dishes such as sashimi, deep-fried dishes, char-grilled dishes and broths. Ingredients also range from various seasonal vegetables, condiments, seafood and meat. Without the versatility to accompany all these aromas and flavours, the meaning of our development as éks KAISEKI would be lost.” The aim was to create a sake that could accompany any dish at any time of the year, regardless of the season, whether it be a summer course with its refreshing ingredients, or winter course with its fatty, rich ingredients.

The brewery that Mr Koizumi thought was closest to his image was Kokuryu Shuzō in Fukui Prefecture, which produces such iconic brands as Kokuryu Ishidaya and Kokuryu Shizuku, both of which are daiginjo sake matured at low temperatures. He has enjoyed drinking the brewery’s sake for a long time, and says that the appeal of their sake is that, ‘it not only tastes good, but also complements the food and you can sense the ‘core’ of the sake, which creates a wonderful synergy of flavours.”

“The brewery’s philosophy is to create a universal taste that is timeless and can be enjoyed by anyone, while at the same time continuing to take on the challenge of creating new and better flavours at the very highest level. I am always impressed by their great philosophy and great sake, and I admire their brand, which inspires me to want to follow suit.”

Naoto Mizuno, the eighth-generation of Kokuryu Shuzō, is a man who is recognised not only in the sake industry, but also within the restaurant industry. Koizumi was worried about whether the brand would be accepted because of its image as a prestigious and exclusive brand. However, he readily agreed to take part in the project because this new, targeted perspective of seeking the ultimate pairing of sake and Japanese cuisine struck a chord with him.

“The brand “ Kokuryu ” itself aims to be a “dining sake” with a delicate umami and moderate flavour that complements cuisine. The sake is designed to be slightly more reserved when it is in its undiluted form, and then aged to give it a gentle, elegant flavour that will complement the food,” says Mizuno. “We are proud of the fact that our existing products are suitable for all kinds of food, but the challenge this time is to focus even more on creating an all-round taste that complements dashi and seasonal ingredients.” Mizuno feels that, “the key is not just to make it beautiful, but to express its multi-layered, complex flavour in an elegant way.”

In the initial design of the sake’s profile, Koizumi tasted existing products, from junmai to alcohol-added styles, and with different rice and yeast, as well as different rice polishing ratios, to get a detailed understanding of the taste he envisioned. As a result, Mizuno decided on the direction to take, saying, “I thought that the gentle aroma and the full-bodied taste that is achieved through maturation are close to the characteristics that our sake has.”

Koizumi then visited the brewery and conducted a series of tastings of sake samples, which were created based on their initial discussions. “Mizuno prepared several samples made from different types of rice varieties and yeast strains. I thought they would use existing undiluted sake, but I was overwhelmed by their enthusiasm in designing the flavour from scratch.” Koizumi experienced the changes in flavour caused by gradually adding water to the prepared samples in 0.5% increments. “I was surprised to see how the taste of the same undiluted sake could change even with just 0.5% water added, and I was impressed by the depth of the sake brewing process, and how they take such a precise approach in deciding the direction of the undiluted sake. It was a most educational experience for me.”

This is how they decided on the direction to take when brewing the sake. In creating the base for a clear, transparent sake with a subdued aroma, careful attention was paid to the ginjo aroma. During the process of making ginjo, which is fermented slowly at low temperatures, the aromatic ingredients are trapped in the moromi (the ferment), producing fruit-like ‘ginjo’ aromas, but if excessive, these aromas can become overpowering and interfere with the aromas of the food. The base was produced with recipes from ’Kokuryu Ishidaya’ and ’Kokuryu Shizuku’ as a reference, then the undiluted sake was matured at low temperatures after it was filtered. The depth of flavour gradually develops over time.

Kokuryu Shuzō began maturing its year-round products for around 10 months, with the exception of their ‘shinshu’ (newly brewed and filtered sake, released at the start of each brewing season), about 50 years ago, when the previous generation of the family brewery was in charge. In 2005, when Mizuno became the eighth generation of the brewery, construction was completed on the new ‘Kenjojima Sakezukuri no Sato’ as a facility to realise thorough low-temperature maturation of undiluted sake. The facilities and the technology in place have been designed to achieve the desired flavour, including the ability to control each room or individual tanks with cooling systems.

In this facility, the optimum temperatures have been selected for maturing, which adds to the multi-layered, complex flavour. After regularly tasting the sake to check its condition, and observing its progress, the image was refined, and finally éks KAISEKI, which gently harmonises with all the delicate and varied aromas and flavours of Japanese cuisine, was completed.