Koizumi Shuzo, a popular stopover on the Boso Peninsula, a tourist destination in Chiba Prefecture, has greatly improved the quality of its ginjo and junmai ginjo class sake since the fourteenth generation, Fumiaki Koizumi, took over. The activities of the fourteenth generation, including rice cultivation in the company’s own rice fields and brewing that brings out the potential of rice grown in Chiba Prefecture, are not to be missed.
Continuously Polished Techniques and the Challenge of Specified Name Sake
Koizumi Sake Brewery is one of the leading sake breweries in the Uchibo region of the Boso Peninsula, facing Tokyo Bay, and in 1996 the former owner built a direct sales shop next to the brewery, the Sommelier House Sakasho no Yakata, which has become a regular stop on tour buses, attracting over 100,000 visitors a year during its peak season.
However, contrary to its touristy image, Koizumi Fumiaki, the 14th and current head of the brewery, has switched from a lineup of mostly plain sake to ginjo-shu, junmai-shu, and other sake with specific designations, and has made more technologically advanced sake the mainstay of his business. Koizumi laughs as he explains, “We are struggling with the gap between the tough image of our brand names ‘Tokai Zakari’ and ‘Tokai’ and the delicate quality of the sake we are promoting now.
A regular winner of the National New Sake Competition, the brewery has continued to refine its techniques from generation to generation.
Koizumi Sake Brewery is located in the countryside at the foot of Mt. Kano. It was founded in 1793 (Kansei 5). The Minatogawa River flows near the premises and flows into Tokyo Bay. During the Edo period, sake was transported to Edo by water.
Koizumi Sake Brewery has three people, including Koizumi, in charge of production, and produces about 250 koku (1 koku = about 180 liters) per year. Although it is a small sake brewery, the proactive attitude towards improving the quality of sake has been passed down from generation to generation. For example, in the early Showa period, they introduced refrigerators and began to make ginjo sake while controlling the temperature. His father, the previous owner, became the master brewer himself, and while he was the manager, he also took charge of the production site as the brewery master brewer, responsible for sake brewing. He worked hard to improve the quality of the sake by receiving feedback through participating in competitions. The current head of the family, Koizumi, is also honing his skills as a master brewer.
The brewery’s attitude of valuing the quality of its sake and its technical capabilities is clearly reflected in its award history. Symbolic of this is the fact that the brewery has a long history dating back to the Meiji era and is a regular winner of the gold award at the National New Sake Tasting Competition, the most prestigious competition in Japan. In 2024 (brewing year 2023), Daiginjo Tokaimori won the gold award. This marks the 13th consecutive year that the brewery has won an award, and the 21st gold award in total. Tokaimori Junmai Ginjo Nanohana, made from Yamadanishiki rice grown in Hyogo Prefecture and polished to 55%, won the special JAL Flying SAKE Award at the SAKE COMPETITION 2024, a sake trend-setting event judged by technical instructors, brewers, and experts from around the country.
The 14th generation’s challenge, starting from scratch
Koizumi majored in physics at university. He joined a semiconductor-related company and “knew nothing about brewing or yeast.” However, in 2009, when his father fell ill, he decided to return to the brewery. At the time, the brewery was still mainly producing regular sake, but sales were declining, and he struggled with his own lack of technical skills and sales. It was truly a “start from scratch.”
“I read all the textbooks, asked people who were making sake, and then put it into practice,” recalls Koizumi. He learned from the Nanbu Toji, a sake brewing group that is counted among the three major Toji in Japan, and is now in charge of the production site as a Nanbu Toji.
Meanwhile, he also began updating the brewery’s equipment. Starting with a rice washer that can adjust the water absorption rate, he gradually introduced a thermal tank, a preparation container with a cooling device, a refrigerated container, and a machine called a pasteurizer that can pasteurize efficiently. Refrigeration equipment is especially important in the warm Chiba prefecture. Considering the recent high temperatures, “the only time we can make sake properly without refrigeration is from December to February.”
In addition to quality control and streamlining, inheriting the passion for honing one’s skills that has been passed down from generation to generation has contributed to improving the quality of the sake. They have been able to expand their lineup of designated name sake, focusing on junmai ginjo class sakes. When Koizumi returned to the brewery, they had almost no business with liquor stores outside of Chiba Prefecture, but now they do business not only within Chiba Prefecture, but also with liquor stores in Tokyo, such as Hasegawa Liquor Store, which is involved in supervising sake books and running sake tasting events and is trusted by top hotels and restaurants.
Brewed with rice grown in our own fields
Koizumi-san inherited more than just the attitude of continuing to hone his skills from his predecessor. He inherited the will of his predecessor, who cared about the site where the raw rice is grown, saying, “Sake brewing starts with rice cultivation,” and he also grows rice in his own fields with his employees.
“This may be a sake that truly reflects the essence of Koizumi Sake Brewery,” he says of “Tokaimori Tokubetsu Junmai Jidoden Gohyakumangoku.” As the name suggests, this sake is brewed with Gohyakumangoku rice, which is suitable for sake brewing and grown in his own fields. The brewery’s own fields, located near the brewery, are about 1.6 hectares in size. The rice harvested from these fields is used for some of the sake brewed by Koizumi Sake Brewery. The rice grown in these fields was Gohyakumangoku. “Was” is in the past tense because the variety of rice grown will be changed from the rice planting in 2024.
Taking on new challenges with rice grown in Chiba Prefecture
In 2024, they planted rice of “Fusanomai,” a type of rice suitable for sake brewing developed by Chiba Prefecture. Although the direct reason for changing the variety was the difficulty in obtaining Gohyakumangoku rice seeds, it was challenging to cultivate Fusa no Mai, which has not yet been brewed in-house. However, Koizumi had high expectations for the potential of rice grown in Chiba Prefecture. This is backed up by the existence of the sake “Junmai Ginjo Tokai Yumekanae.”
“Yumekanae” is a low-glutelin rice variety developed by Chiba Prefecture. Glutiten is a type of protein, and when brewed with low-glutelin rice with a low glutelin content, it has a major characteristic of taking on a ginjo aroma reminiscent of lychee. “I would recommend this to wine lovers and sake beginners,” says Koizumi, and this sake, made from 100% Yumekanae, has now become one of Koizumi Sake Brewery’s standard sakes.
Of course, Koizumi Sake Brewery sometimes purchases Yamada Nishiki, a type of rice suitable for sake brewing, from outside Chiba Prefecture, but Koizumi emphasizes the significance of brewing with rice grown in Chiba Prefecture, saying, “There is also the fun of bringing out the unique characteristics of Chiba rice.” What kind of sake will be born from Sounomai, grown in Koizumi’s own rice fields? Since “Gohyakumangoku” has received a certain amount of acclaim, expectations are already building.
Koizumi wants to continue exploring the possibilities of rice grown in Chiba Prefecture. In addition, he wants to increase the cultivated area of his own rice fields. This is because “the number of rice fields that cannot be cultivated is increasing due to the aging of the local population.” Until now, the local people have also grown the rice used as raw materials. It is his desire to give back to them that has led him to turn his attention to rice farming. His constant efforts to hone his skills and his love for his hometown will continue to produce sake that brews the culture of Chiba and the Uchibo region.
