Chugoku Electric Power Co., Inc. Sumikawa Power Station Main

A Modernist Statement in a Mountain Wilderness

The Sumikawa Power Plant Main Building was completed in July 1943, in the middle of the Pacific War. While most attention in Japanese architectural history focuses on the great urban structures of Tokyo, Osaka and Kyoto, this building represents something quieter and arguably more surprising: the early arrival of European-influenced modernism in one of the most isolated valleys of the Chugoku Mountains.

Constructed of reinforced concrete finished in mortar plaster, the structure is composed of two volumes arranged in a staggered, echelon-style plan. To the south stands the tall, single-storey generator hall, which contains a soaring interior space and extends two levels below ground to house the turbines and water passages. To the north, slightly offset, rises a two-storey administrative wing that once served as the office and operations centre. The total floor area is a modest 346 square metres, but the proportions are commanding.

What makes the building so striking is its complete absence of decorative ornament. There are no carved details, no historicist references, no mouldings to soften the volumes. Instead, the architect relied on the geometry of the masses themselves and the rhythm of plain rectangular windows to create visual interest. This austerity reflects both the international modernist movement that had reached Japan in the 1920s and 1930s and the strict wartime ethos of plain, functional construction known as the "spirit of frugality and substance."

Why It Was Designated a Cultural Property

On 26 March 2015, the Sumikawa Power Plant Main Building was added to the Agency for Cultural Affairs' register of Tangible Cultural Properties (Buildings). The designation recognises three intertwined values that make this remote power station nationally significant.

The first is its rarity as an example of pure modernist architecture from the wartime period. By 1943, steel was rationed, decorative materials were prohibited, and most large construction projects had ceased entirely. That a substantial reinforced-concrete industrial building was completed at all in this year is unusual. That it was designed in a confident, internationalist style rather than the nationalist Imperial Crown Style ("Teikan-yoshiki") that dominated state architecture of the time makes it doubly so.

The second is its place in the regional history of electrification. The Hikimi River basin saw some of the earliest hydroelectric development in western Honshu, and Sumikawa was the third in a chain of plants that included the Hikimi Power Plant (1928) further upstream and the Toyokawa Power Plant (1928) downstream. Together they formed the backbone of electrical supply for a vast rural area.

The third is its remarkable state of preservation. More than eight decades after its construction, the building still functions as an active power station generating roughly 10,100 kilowatts. The exterior, the spatial composition and the interior of the generator hall all retain their original character, allowing visitors to read the design intentions of the wartime architects with unusual clarity.

Highlights for the Visitor

Approaching the building from the narrow mountain road that follows the Hikimi River, the first impression is one of unexpected sophistication. The plain white walls, the strong horizontal lines of the parapets and the careful asymmetry of the staggered plan all speak of a design sensibility far removed from rural Japan of the 1940s. The building sits in conversation with the river and the steep wooded slopes around it, its geometric volumes contrasting beautifully with the organic landscape.

Visitor Information

The Sumikawa Power Plant remains an active operational facility owned by the Chugoku Electric Power Company. The interior is not generally open to the public, but the exterior can be appreciated and photographed from public roads in the surrounding area. Visitors are asked to respect the privacy and operations of the working plant and to refrain from entering company property.

The plant is located in the Hikimi district of Masuda City, in the far southwestern corner of Shimane Prefecture. Public transport to this remote area is limited, and a rental car is strongly recommended. From JR Masuda Station, the journey by car takes approximately one hour and twenty minutes via local roads following the Hikimi River. Bus services from Masuda Station serve the Hikimi-kyo Onsen area, from which a taxi may be required for the final leg.

Drivers approaching from the south can reach the area in roughly an hour from the Togouchi Interchange of the Chugoku Expressway via National Route 191 and prefectural roads. Mountain roads are narrow and winding; in winter, heavy snowfall can make access challenging, and snow tyres or chains are essential.

Surrounding Attractions

Hikimi is renowned for the spectacular Hikimi Gorge (Hikimi-kyo), one of the most beautiful river canyons in western Japan. The gorge is divided into four distinct sections — Mae-Hikimi, Oku-Hikimi, Omote-Hikimi and Ura-Hikimi — each offering its own character. Omote-Hikimi extends for about four kilometres of gentle scenery and clear streams, while Ura-Hikimi features dramatic cliffs and a chain of waterfalls including the Five-Tier Falls. Oku-Hikimi is famous for the 53-metre Daryuzu Waterfall and a community of wild rhododendrons.

Autumn is the most celebrated season for visiting the gorge, when the surrounding deciduous forests turn brilliant red and gold. Spring brings fresh greenery and wildflowers, and summer offers a cool retreat from the heat of the lowlands. Hikimi-kyo Onsen, a hot spring resort with accommodation and bathing facilities, makes a comfortable base for exploring the region.

Other points of interest in Hikimi include the Mino-ji Yashiki, the historic residence of an Edo-period village headman, which is itself a Registered Tangible Cultural Property. The wider Masuda area offers the historic castle town of Tsuwano about an hour to the south, the Iwami Kagura sacred dance tradition and the spectacular sunsets of the Sea of Japan coast.