Nobu first experienced the wonders of Hokusetsu Saké shortly after the opening of Matsuhisa in 1987, when his friend, famed Japanese rock-musician Eikichi Yazawa, brought a bottle to the restaurant. Typically, the sweetness of saké makes the drink more enjoyable served hot. However, the Hokusetsu that Yazawa had brought was wonderfully smooth, even when served chilled. Nobu decided to replace the saké on his menu with brews from Hokusetsu.

Hokusetsu is located in Sado, the largest island in the Sea of Japan. Sado is known for its harsh winters. This climate is a key factor for the quality of Hokusetsu products, as sake is brewed during the coldest days of the year. The Hazu Family began as purveyors of saké in 1871 and started producing original brews in 1886. The brewery adopted the name Hokusetsu, meaning "Northern Snow," in 1993. Hokusetsu produces uncompromisingly dry saké products, many of which have been awarded Japan's most coveted prizes for brewery.

One of the most famous Hokusetsu products is Ongaku-shu, literally translated as “musical saké.” Connoisseurs claim that saké that have been shipped by boat have a deep taste, since the saké is smoothened by the undulating motions of the waves. To recreate the wave-effects, Hokusetsu plays the New Age music of Japanese composer Kitaro to the bottles of Ongaku-shu for three years in a special cellar.

In its never-ending dedication to improve the quality of its products, Hokusetsu commissioned the world's first titanium saké containers in 1987, to keep ultraviolet light from spoiling the saké. In 1990, Hokusetsu began exporting to the United States and currently sells its saké products and beers exclusively through the Nobu and Matsuhisa restaurants for the overseas markets.

Robert De Niro visited Hokusetsu in 1998 when he was in Japan for the opening of Nobu Tokyo. A saké connoisseur, De Niro prefers to drink his favorite Hokusetsu saké from a wooden cup made from the Japanese cypress tree, with a little salt sprinkled on the rim of the cup. De Niro, even today, remembers Sado as Saké Island.

Making Sake
The basic ingredients of saké are rice and water. Most saké in Japan are produced in large modern factories that utilize stainless steel vats, biochemistry and computers in the production process. The basic brewing techniques, however, have changed very little since the 1500s, when saké was first produced. Hokusetsu, and many other small breweries, have not abandoned the traditional methods and some brews, such as Junmai Daiginjo, are still made almost entirely by hand. Saké is a “living” product, and variations in taste occur due to the quality of the ingredients, the weather conditions at the time of brewing, the brewing temperatures used, and the skills of each worker involved. Ultimately, the success of the brewing process is determined by the experience and intuition of the master brewer, or toji. Saké is brewed on the very coldest days of winter using rice harvested in the autumn. The brewing process is completed around April.

Rice Polishing
RicePolishing Saké is made from polished rice. Brown rice is milled and the smaller white rice grains that remain are used for the brewing. Brewers have known for many years that the fineness of flavor of the saké is directly correlated to the extent the rice is polished. Generally, the rice used in brewing is polished to approximately 80% of its original size. For some top grade sake, it is polished to less than 40%. Saké is often classified according to the extent of polish; Hokusetsu's brews range from 68% to 35% for its two flagship brands, Daiginjo KK35 and Daiginjo YK35.
Washing , Steeping and Steaming
Nuka, or rice powder, remains on the surface of polished rice, and is removed by washing. Gentle hand-washing is required for top grades of saké, which use delicate rice that have been polished to less than 50%. The rice is then soaked to allow the grains to absorb water. The highly polished rice absorbs water very quickly. While rice that has been polished to only about 75% is usually left to soak overnight, highly polished rice will be steeped in water for only a few minutes. Hokusetsu generally steeps its rice for about five minutes. The rice is then steamed to produce the koji (saké mold) and to sterilize the rice. The steamed rice is then divided and cooled.

Making Koji Rice
Koji is a mold (Aspergillus oryzae) which converts starch into sugar and breaks down proteins. Approximately 20% of the steamed rice is cooled to about 86˚F (30˚C) and transferred to a special double-walled sauna-like room. Here, dried koji spores are scattered over the rice and kneaded in to distribute them evenly. After a few hours the rice is moved to shallow wooden trays which are placed on shelves and covered with cloth. As the koji mold develops, the temperature of the rice rises. To ensure that the temperature does not rise too high, workers stir the rice every four hours. After forty-eight hours, the boxes containing koji are removed from the room, stopping the growth of the bacteria. The koji is then combined with steamed rice, water and yeast to make the basic mash, or moto.

Making Moromi and Fermention
The ingredients of the main mash or moromi (water, koji and steamed rice) are added to the moto in three stages over four days. This is called san-dan jikomi. Increasingly large amounts of these ingredients are added to the moto on the first, third and fourth days. This final mash is left to ferment for thirty days and results in a moromi with17.5% alcohol content.

Pressing and Filtering
Almost all saké is now pressed in automatic pressing machines. A traditional fune press is also used for certain brews at some breweries. The moromi is poured into long bags (saka-bukuro) and stacked in the deep rectangular body of the press. For the first few hours, the saké trickles out under its own weight; later, a heavy lid is lowered and pressure is slowly applied. The following day, the bags are restacked and pressed once again. The fresh saké is called shin-shu or "new saké." The caked lees that remain in the bags are called saké kasu, and are used in pickle-making and cooking.

Saké is pasteurized at 140˚F (60˚C) and then transferred to vats, where it is aged for about three months. Before bottling, the brewer will add water to dilute the saké to a level of between 15% and 17% alcohol and re-pasteurizes the sake.

Some Hokusetsu sake, most notably Hon-jozo Kinpakun and Ongaku-shu, are left to mature in dark, cool cellars. Unique to Hokusetsu is the special treatment given to the bottles of saké during storage. Onigoroshi is kept at temperatures below 32˚F (0˚C). (Saké freezes at 6˚F (-15˚C).) Hokusetsu has also installed special ultrasonic wave equipment to mellow some of its brews, such as Cho-juku-shu. A variation of this technique is used for its Ongaku-shu: stereo equipment plays the New-Age music of a Kitaro, a renowned Japanese composer, to this saké for three years, with the music acting as an emulation of the vibrations of the waves of the sea. It is believed that the undulating motion of the waves adds richness to saké that has been transported by boat over long distances.