Brewer Yuji Shimada carefully holds the stem of a short wine glass and pours a clear, golden liquid from one of the taps mounted on the commercial refrigerator, the light fizz from natural carbonation creating a thin layer of foam reminiscent of beer head.

“This is what we call the ‘original’ with no additional flavoring, just the basic ingredients: green tea, black tea, sugar and the fungus for fermentation,” the bespectacled 42-year-old says.

“We’re the only brewery in Japan with a license to produce nonheated kombucha.”

Here at Oizumi Kojo, a company located in the industrial quarters of Kawaguchi, a city in Saitama Prefecture, Shimada and his assistant are running the nation’s first commercial-scale brewery producing kegs of unpasteurized “raw” kombucha, the tea-based functional beverage that’s become a multimillion-dollar industry in the United States, where its purported health benefits have made it a favorite among city-dwelling millennials, models and athletes.

Shimada pours a glass of kombucha at Oizumi Kojo’s kombucha brewery in Kawaguchi, Saitama Prefecture. | YOSHIAKI MIURA

It was once a big thing in Japan, too, around four decades ago and under a different moniker. Back then it was called kōcha kinoko (mushroom tea) a name derived from how the “scoby” — short for the symbiotic culture of bacteria and yeast and an ingredient used in the fermentation process of kombucha — resembles a mushroom.

There are various theories regarding the origins of the drink, with some dating it back to 200 B.C. in Manchuria. It is thought to have eventually made its way to Russia, where lore has it that inhabitants of a Siberian village near Irkutsk on Lake Baikal were living to a ripe old age thanks to the beverage made from the mysterious fungi.

It became a sensation in Japan when a book hailing its health benefits was published in 1974 by a widow in her 70s who said she received a piece of the jelly-like fungus from a Japanese who brought it back from the Siberian village. The book came with a coupon that offered a slice of the fungus if readers sent them in with a return address, and soon households began homebrewing their own probiotic drinks in glass jars, claiming it could prevent ailments and diseases ranging from constipation to cancer. But the boom soon died out after medical experts began to question its benefits.

The funky tea then made its way to South Korea, and finally to the U.S., where it was commercialized in the mid-1990s by a young entrepreneur named GT Dave, who founded GT’s Kombucha, which remains the leading American brand for the drink.

Now Japan seems to be cautiously catching on to the trend it once embraced so fervently. But the concoction’s new alias may be a marketing obstacle: In Japanese, kombucha typically refers to a type of tea made from kombu (seaweed).

Kombucha’s etymology remains a mystery.

The American Heritage Dictionary says it probably comes from the Japanese kombucha: “The Japanese word perhaps being used by English speakers to designate fermented tea due to confusion or because the thick gelatinous film produced by the kombucha culture was thought to resemble seaweed.” Fans of the beverage are said to affectionately call it “booch.”

In any case, it’s already an established international name for the drink, says Kantaro Oizumi, the 37-year-old president and CEO of Oizumi Kojo, a century-old company that used to run a casting factory and now primarily brings in revenue through real estate.

Kantaro Oizumi, president and CEO of Oizumi Kojo, sits outside his kombucha brewery. Captivated by the health drink, Oizumi decided to launch Japan’s first full-scale kombucha brewery in 2016 with the help of brewer Yuji Shimada. | YOSHIAKI MIURA

Oizumi, who used to work for Parco Co., a major chain of department stores, took over the family business a decade ago, and began branching out to new enterprises. He first set his eyes on importing popcorn machines, and soon became interested in organic food. His business took him on frequent trips to the U.S., where he would routinely scour supermarkets and grocery stores to see was trending.

“Every year there seemed to be more drinks labeled kombucha. I tried it, and it tasted good and felt good.”

Oizumi continued to explore the allure of the drink, attending seminars and talking to experts. “I learned how the kombucha business was growing overseas, and in 2016 decided we want to get involved,” he says. This was also around the time he met Shimada, then a brewer working at sake-maker Kiuchi Shuzo’s craft beer brewery. Oizumi would soon bring him into the fold.

“I knew nothing about kombucha, but I did some research and made some of my own,” recalls Shimada, adding that the process shares many similarities to brewing beer.

“I eventually decided to join the company and began building the brewery from scratch.”

Shimada imported the scoby from the U.S. and began assembling equipment, including those used for winemaking and craft beer-brewing. He strived for an ecologically friendly design and connected the devices online so the plant could be monitored and managed remotely if necessary.

Oizumi Kojo’s kombucha uses organic green tea and black tea leaves produced by Kyoto’s Nagata Chaen. The fermentation process can take a week or longer, during which the sugar and tea creates a beverage with a slightly sweet and tart flavor.

Brewer Yuji Shimada and his assistant sort used green tea and black tea leaves, which will be recycled as fertilizer. Shimada designed the kombucha brewery to be ecologically friendly, striving to produce minimum waste. | YOSHIAKI MIURA

The Kombucha Brewers International says, “the sugar feeds the yeast, which creates CO2 and ethanol, then the bacteria consume the ethanol and convert it into healthy acids.”

After the initial fermentation is over, Shimada adds flavorings ranging from yuzu citrus to mint and grapes. He has so far created around 30 different flavors of kombucha, some of which can be tasted at Oizumi Kojo Nishiazabu, a wholly owned restaurant in Tokyo’s Minato Ward that serves the beverage on tap, as well as cold pressed juice and other health drinks and food. Shimada says Oizumi Kojo delivers kombucha kegs to around 20 or so bars and restaurants that serve craft beer and hopes to expand its distribution channel to yoga studios and sports clubs, as well as organic food stores. The brewery has an annual maximum production capacity of 60,000 liters and is considering constructing another plant if demand exceeds its current limits.

Kombucha is a rapidly expanding industry. According to the Kombucha Market Report by Orbis Research, the global market size for the drink is expected to grow from $970 million in 2017 to $3.81 billion in 2023 with a compound annual growth rate of 25.6%.

The market in Japan remains subdued so far, although there are hints it could go mainstream as models and celebrities openly declare their love for the fermented drink. Imported cans and bottles of kombucha are sold in select supermarkets and the beverage is served in organic restaurants and cafes that often make their own, while Ferment Works, based in Wakayama Prefecture, has been selling domestically produced pasteurized kombucha online for some years now.

Headlines suggesting a potential revival of the health drink have been landing in magazines and newspapers with increasing frequency.

“At this stage we are the only full-scale kombucha brewery in Japan, but I think other breweries will eventually emerge,” Oizumi says.

“We want to go toe-to-toe with overseas brewers and bottle our products and build a larger manufacturing plant. And we want to welcome newcomers with a sense of camaraderie so all of us can expand kombucha’s potential together.”

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