Irago Tōdai-ji Tile Kiln Ruins: Where the Great Buddha's Roof Was Born

On the windswept tip of the Atsumi Peninsula in Aichi Prefecture, an unassuming hillside holds one of Japan's most compelling archaeological secrets. The Irago Tōdai-ji Tile Kiln Ruins (伊良湖東大寺瓦窯跡) mark the very site where massive roof tiles were fired for the Kamakura-period reconstruction of Tōdai-ji, one of Japan's most iconic Buddhist temples. Designated as a National Historic Site in 1967, this kiln complex connects the remote shores of Mikawa Province to the spiritual heart of Nara, revealing an extraordinary story of medieval craftsmanship, logistics, and devotion.

Historical Background: The Burning and Rebirth of Tōdai-ji

In 1180, during the Genpei War that tore Japan apart, the forces of Taira no Shigehira set fire to the great temple of Tōdai-ji in Nara. The blaze consumed the Daibutsuden (Great Buddha Hall) and much of the surrounding complex, devastating one of the nation's most sacred religious sites. The destruction sent shockwaves across Japan.

The ambitious task of rebuilding fell to the Buddhist monk Shunjōbō Chōgen (1121–1206), who was appointed to the position of chief fundraiser and project director for the reconstruction. Despite being over 60 years old at the time, Chōgen traveled tirelessly across the country, securing funds, sourcing timber, and arranging for the production of the enormous quantity of roof tiles needed for the new Great Buddha Hall. The reconstructed Daibutsuden was completed and consecrated in 1195.

Chōgen identified two key sites for tile production: Mantomi in Bizen Province (present-day Okayama Prefecture) and Irago on the Atsumi Peninsula in Mikawa Province (present-day Aichi Prefecture). The Atsumi Peninsula had long been a territory of Ise Grand Shrine, and its kilns were renowned for producing high-quality ceramics. Chōgen's connections with senior priests of Ise Grand Shrine likely facilitated the commissioning of tiles from this region.

Discovery and Archaeological Significance

Although local legend had long held that tiles for Tōdai-ji were once fired in the Irago area — the locality even bore the place-name "Kawaraba" (tile field) — it was not until 1966 that physical evidence confirmed these traditions. During the construction of the Hatsutachi Reservoir, part of the Toyokawa irrigation system, workers uncovered the remains of ancient kilns on the south-facing slope of the dam embankment.

Excavations conducted from 1966 to 1968 revealed three anagama (tunnel-type) kilns carved into the hillside at elevations between 11.5 and 14.5 meters. Among the most remarkable finds were eaves tiles bearing the inscription "Tōdaiji Daibutsuden Kawara" (東大寺大佛殿瓦), meaning "Tōdai-ji Great Buddha Hall Tile." This seven-character inscription, arranged around the circular face of the decorative end tiles, provided unmistakable proof that these kilns supplied roofing materials for the Kamakura-period reconstruction.

Further confirmation came in 1968 when Tōdai-ji's bell tower underwent roof repairs. Among the old tiles removed during the work, flat tiles inscribed with the character "Tō" (東, meaning "east") were found to match tiles excavated at the Irago site — a direct physical link spanning some 300 kilometers and over 800 years of history.

In addition to roof tiles, the excavation yielded kawara-kyō (tile sutras), kawara-tō (tile pagodas), and other religious artifacts, as well as everyday items such as jars, pots, and small dishes. A total of 455 excavated objects, now housed at the Atsumi Folk Museum, were designated as Aichi Prefectural Cultural Properties (archaeological material) in 2020.

Why Was This Site Designated a National Historic Site?

The Irago Tōdai-ji Tile Kiln Ruins received National Historic Site designation on December 11, 1967, for several compelling reasons. The site provides tangible evidence of the massive logistical network that supported one of medieval Japan's greatest architectural undertakings. It demonstrates the high level of ceramic technology achieved by the Atsumi kilns during the late Heian and Kamakura periods, a tradition that also produced the celebrated Atsumi ware. Furthermore, the inscribed tiles offer rare primary evidence of the organizational structure behind Tōdai-ji's reconstruction, linking this remote peninsula directly to the cultural and religious center of Nara.

The site is one of only two designated tile kiln sites associated with the Kamakura-period Tōdai-ji reconstruction, the other being the Mantomi Tōdai-ji Tile Kiln Site in Okayama. Together, they illustrate the nationwide scope of this monumental project.

What to See at the Site

Today, the three excavated kilns have been backfilled for preservation, but their locations are clearly marked with stone outlines set along the hillside contours. Informational signboards at the site explain the history of the kilns and the significance of the discoveries. Visitors can walk the gentle slope and appreciate the scale of the kiln structures — the largest measured over 11 meters in length — while imagining the intense heat and labor that once filled this hillside.

The site is located immediately south of Hatsutachi Reservoir, a scenic irrigation pond surrounded by greenery. The tranquil setting, with views across the reservoir and surrounding woodland, makes for a peaceful visit. The area is particularly attractive during the spring cherry blossom season and autumn foliage.

A Fascinating Detail: Tiles Without Sanskrit

An intriguing difference exists between the tiles produced at Irago and those made at the Mantomi kilns in Okayama. While both sites produced eaves tiles with seven-character inscriptions, the Irago tiles bear only kanji characters spelling out "Tōdaiji Daibutsuden Kawara." The Okayama tiles, by contrast, include a Sanskrit (Siddhaṃ) character representing the Vairocana Buddha at their center, omitting the character for "tile." Some researchers speculate that the Irago craftsmen, working in a region closely tied to Ise Grand Shrine and Shinto traditions, may have chosen to avoid the unfamiliar Buddhist script — a small but telling detail that hints at the cultural dynamics of medieval Japan.

Atsumi Folk Museum: Seeing the Artifacts Up Close

To fully appreciate the significance of the Irago tile kilns, a visit to the Tahara City Atsumi Folk Museum (田原市渥美郷土資料館) is highly recommended. Located in the Atsumi district of Tahara City, the museum's archaeological gallery displays excavated eaves tiles, flat tiles, religious objects, and everyday ceramics from the kiln site. Seeing the actual inscribed tiles — each weighing around 7 kilograms — brings the scale and ambition of the medieval tile-making operation vividly to life.

The museum is open from 9:00 AM to 5:00 PM (last entry at 4:30 PM), closed on Mondays (or the following weekday if Monday is a national holiday) and during the year-end/New Year period (December 28 – January 4). Admission is free.

Surrounding Attractions

The Irago area at the tip of the Atsumi Peninsula offers a wealth of natural beauty and cultural interest beyond the kiln ruins.

• Cape Irago and Irago Lighthouse: The scenic cape at the peninsula's tip offers dramatic coastal views and the historic lighthouse, a beloved landmark since 1929.
• Koiji-ga-hama Beach: Known as "Lovers' Beach," this romantic stretch of white sand faces the Pacific Ocean and is one of the region's most photographed spots.
• Hatsutachi Reservoir: Adjacent to the kiln ruins, this peaceful irrigation reservoir is ideal for a quiet stroll and birdwatching.
• Irago Nanohana Garden: From January through March, over 10 million rapeseed flowers turn the fields brilliant yellow, creating a stunning seasonal landscape.
• Michi-no-Eki Irago Crystal Port: This renovated roadside station near the Ise Bay Ferry terminal offers local produce, dining, and information about the peninsula.
• Sarayaki Old Kiln Museum (皿焼古窯館): Another historic kiln site in the area, offering further insight into the Atsumi Peninsula's rich ceramic heritage.

Getting There

The kiln ruins are located in the Irago-chō area of Tahara City, about 100 meters east of National Route 259. By public transport, take the Toyotetsu Bus Irago Main Line from Mikawa-Tahara Station and alight at "Kameyama-nishi" bus stop; the site is approximately a 30-minute walk from there. By car, the site is near Hatsutachi Reservoir, with signage from Route 259 indicating "Hatsutachi Dam 1.0 km" and "Tōdai-ji Tile Kiln Ruins 1.0 km." Free parking is available. Visiting the site and the adjacent reservoir area is also free of charge.