Sakkai Soy Sauce Industry Hydraulic Storage Machine Shed

Sakai Soy Sauce Industry Hydraulic Accumulator Shed: A Hidden Gem of Industrial Heritage on Shodoshima Island

Tucked along a prefectural road in the Nouma district of Shodoshima Island, Kagawa Prefecture, stands a remarkably small yet historically significant wooden structure — the Sakai Soy Sauce Industry Hydraulic Accumulator Shed (左海醤油工業水圧式蓄量機小屋). Registered as a national Tangible Cultural Property in 2002, this modest cedar-bark-roofed shed houses a rare hydraulic accumulator device that once powered the moromi (soy sauce mash) pressing machines at the Sakai Soy Sauce brewery. It is one of the precious surviving relics that illustrate how Japan's traditional soy sauce brewing industry embraced modern technology during the early Showa period.

The History of Sakai Soy Sauce and Shodoshima's Brewing Heritage

Shodoshima Island, situated in the calm waters of the Seto Inland Sea, has been one of Japan's four major soy sauce production regions for over 400 years. Soy sauce brewing on the island traces its origins to the Bunroku era (1592–1595), when stone-quarrying crews working on Osaka Castle brought soy sauce from the Yuasa region of Kii Province. Fascinated by this seasoning, islanders traveled to Yuasa to learn the craft and brought brewing techniques back to Shodoshima.

The Sakai family originally operated a maritime shipping business before beginning soy sauce production around 1857 (Ansei 4). Over the following decades, Sakai Soy Sauce established itself as one of the prominent breweries in the Nouma area, which became the heart of Shodoshima's soy sauce district known today as Hishio no Sato (醤の郷, "the Village of Fermented Seasonings"). In 1907, the company participated in founding the major Marukin Soy Sauce enterprise. Then in 1910, Sakai Soy Sauce won a bronze medal at the Japan–British Exhibition held in London, demonstrating that the quality of Shodoshima soy sauce had achieved international recognition.

The brewery buildings constructed during the Meiji and Taisho periods — including soy sauce warehouses and the hydraulic accumulator shed — have been designated by the Agency for Cultural Affairs as Registered Tangible Cultural Properties. Today, Sakai Soy Sauce continues to produce artisanal soy sauce using traditional wooden barrel fermentation, and is particularly renowned for its "saishikomi shoyu" — a premium double-brewed soy sauce that requires twice the raw materials and time of standard production.

What Is a Hydraulic Accumulator and Why Does It Matter?

The hydraulic accumulator (水圧式蓄量機, suiatsu-shiki chikuryōki) housed within this small shed was an essential piece of industrial machinery in the soy sauce pressing process. In traditional soy sauce production, fermented moromi mash must be pressed to extract the raw soy sauce liquid. While earlier methods relied on manual labor or simple lever presses, the introduction of hydraulic technology in the late 19th and early 20th centuries represented a major leap forward in efficiency and output.

The device preserved in this shed features a distinctive mechanism: five tiers of concrete blocks arranged in an "igogumi" (井籠組, crib-stacking) formation, designed to move vertically along guide rails attached to the shed's outer columns. By utilizing water pressure, the accumulator stored and released hydraulic energy to drive the moromi pressing machines, enabling much greater pressing force than manual methods could achieve. This technology allowed breweries like Sakai to increase production while maintaining the quality of their soy sauce.

The shed itself is a modest wooden single-story structure with a gable roof covered in cedar bark (杉皮葺), measuring approximately 2.4 meters on each side with a total building area of just 5.8 square meters. Its small size belies the significance of the machinery it protects — a tangible link between Shodoshima's artisanal brewing traditions and the wave of industrial modernization that swept through Japan's food production industries in the early twentieth century.

Why It Was Registered as a Tangible Cultural Property

The Sakai Soy Sauce Industry Hydraulic Accumulator Shed was registered as a national Tangible Cultural Property (登録有形文化財) on June 25, 2002, under the criterion of being "something that cannot be easily reproduced" (再現することが容易でないもの). This designation recognizes structures of historical, cultural, or technological value that merit preservation for future generations.

Several factors contribute to this property's significance. First, hydraulic accumulator devices of this type were once used in soy sauce breweries across Japan during the modernization period, but very few survive intact today. The combination of the original machinery still housed within its purpose-built shed makes this an exceptionally rare example of early industrial heritage in the food production sector. Second, the structure stands as physical evidence of the technological transition in Shodoshima's soy sauce industry — from purely manual, craft-based production toward mechanized processes that could meet growing demand while preserving traditional quality. Third, as part of the broader Sakai Soy Sauce brewery complex, the shed contributes to the historic landscape of the Hishio no Sato district, where dozens of Registered Tangible Cultural Properties collectively tell the story of Shodoshima's soy sauce heritage.

Highlights and What to See

Visiting the hydraulic accumulator shed offers a uniquely intimate encounter with Japan's industrial heritage. Unlike grand castles or elaborate temple architecture, this tiny structure invites visitors to appreciate the ingenuity embedded in everyday industrial life. The weathered wooden walls and cedar bark roof blend naturally into the surrounding streetscape of brewery buildings, creating a scene that feels genuinely unchanged from decades past.

While the shed itself is compact, its context within the broader Hishio no Sato district makes it part of a richly rewarding walking experience. The Nouma area features a remarkable concentration of historic soy sauce warehouses, many of which are also Registered Tangible Cultural Properties. The dark wooden walls of the brewery buildings, the faint aroma of soy sauce lingering in the air, and the quiet rhythm of a working production district create an atmosphere that transports visitors back to the height of Shodoshima's brewing golden age.

Visitors interested in understanding the full scope of soy sauce production should also explore the nearby Marukin Soy Sauce Memorial Museum, housed in a massive Taisho-era gabled factory building that is itself a Registered Tangible Cultural Property. The museum offers hands-on moromi pressing experiences and features exhibits on the island's brewing history. The combination of the museum visit with a walk through the brewery district, including a stop at the Sakai hydraulic accumulator shed, provides a comprehensive picture of how traditional craft and modern technology have coexisted in Shodoshima's soy sauce industry.

Exploring the Surroundings: Hishio no Sato and Beyond

The hydraulic accumulator shed is located within Shodoshima's celebrated Hishio no Sato district, where more than 20 soy sauce breweries and tsukudani (simmered delicacy) factories line the streets. This area has been recognized as a Modern Industrial Heritage site by Japan's Ministry of Economy, Trade and Industry, acknowledging its outstanding collection of historic brewing infrastructure.

Within walking distance, visitors can explore several notable soy sauce breweries that welcome visitors. Yamaroku Soy Sauce offers tours of its traditional wooden barrel fermentation vats, some of which have been in continuous use for over 150 years. Shokin Soy Sauce preserves the district's oldest brewing warehouse. At the Marukin Soy Sauce Memorial Museum, the famous soy sauce soft-serve ice cream is a must-try treat that surprises visitors with its caramel-like sweetness.

Beyond the soy sauce district, Shodoshima offers abundant attractions. The Shodoshima Olive Park celebrates the island's status as the birthplace of olive cultivation in Japan. The dramatic Kankakei Gorge, one of Japan's three most beautiful gorges, features spectacular autumn foliage and a scenic ropeway. The Twenty-Four Eyes Movie Village recreates the setting of the beloved 1954 film based on the Shodoshima-set novel. Angel Road, a sand bar that appears at low tide connecting small islands, has become one of the island's most photogenic spots.