You will experience the wonder of water that is "hard yet soft."

The unique brewing water used in Matsu's sake brewing is natural water filtered through the Chichibu Mountains, a chain of limestone mountains formed by the uplift of the sea due to tectonic movements. Rain that falls on Mt. Chichibu is filtered through the limestone, passes through the mountains, and becomes underground water, which over the course of several decades flows underground here in Ogawamachi. At our brewery, we pump this water from 130 meters underground and use it as brewing water.

This mineral-rich natural water promotes yeast growth, creating the distinctive umami, crispness, and roundness. Furthermore, by using low-temperature fermentation tanks, we can ferment the sake at a lower temperature than usual, resulting in sake with the mellowness and depth that is unique to Teisho.

Our brewery has always been particular about the rice that is the raw material used in sake brewing. Each type of rice has its own unique flavor and aroma, and we use rice carefully selected from all over the country to suit the quality of sake we aim for, such as "Yamada Nishiki" from Hyogo Prefecture, "Bizen Omachi" from Okayama Prefecture, "Sake Musashi" from Saitama Prefecture, and "Yamazake No. 4 (commonly known as Tamanae)" from Yamagata Prefecture.

For sake brewing, we use rice specifically for sake brewing, known as "sake-brewing rice," which has larger grains than the rice you normally eat. Rice for eating is polished about 7-8% from the brown rice state, but at our brewery, we polish it at least 30%. The reason we polish rice is because the surface of the rice is rich in protein and other nutrients, which can result in an unpleasant taste when made into sake. Polishing the rice is necessary to make fragrant, flavorful sake. However, polishing the rice too much will remove the unique flavor and characteristics of the rice, so we carefully consider each individual feature and polish it to the extent that it brings out the most delicious flavor.

Fermentation tanks are the lifeblood of sake brewing, and are the equipment that controls fermentation. At our brewery, we use the latest low-temperature fermentation tanks and computers to meticulously control the temperature so that the brewer can reliably maintain the temperature range he aims for.

Depending on the type of sake, fermentation takes about 50 days, counting from the time of yeast production. As mentioned above, the brewing water is natural water rich in minerals that promote yeast growth, so by using this tank to ferment slowly at a lower temperature, we can create sake with a fruity aroma and a unique mellow taste.

Our brewery uses a large filter-type press. This is done to prevent the mash from coming into contact with air and losing the aroma that is unique to high-quality sake such as ginjo sake. This press is made up of alternating aluminum and rubber plates, which are hydraulically clamped together to prevent the mash from spilling. By passing the mash between these plates, it can be pressed without coming into contact with air at all. Freshly pressed unpasteurized sake and ginjo sake are immediately stored in the refrigerator, while other sake is sent to the storage room to await aging. For daiginjo sake, we use the traditional method of "fukuro-tsurigiri," which presses the mash using only its weight.

There are two important fungi in making sake: "koji" and "yeast." "Koji" is a type of mold that converts rice starch into sugar. "Yeast" eats the sugar produced by koji and produces alcohol and umami components.
*When yeast produces alcohol, it also produces carbon dioxide gas, which is why new sake contains carbon dioxide.

There are many different types of koji mold and yeast, and just like with sake rice, our brewery uses them according to the quality of sake we are aiming for.
The secret to making delicious sake is to control the action of these koji and yeast, so the process is carried out with the utmost care.