Ruins of Kodo-Ji Temple

Kōdōji Temple Ruins: An Ancient Temple Read Back Out of the Ground

On a low river terrace in the town of Mihama, Fukui Prefecture, a field of farmland marks the spot where a Buddhist temple once stood for more than two centuries. Nothing rises above the soil today, yet archaeologists have recovered the plan of the whole complex: a main hall, a pagoda, a lecture hall, and two gates, each leaving the rectangular earthen platform on which it once sat. The site is known as the Kōdōji Temple Ruins, after the Kōdōji district where it lies.

What makes the place unusual is not a surviving building but a surviving story. Most ancient temple sites in northern Japan are known only in fragments. Here, patient excavation has reconstructed the entire arc of the temple, from the moment a local family raised its first hall in the late 7th century to its abandonment around the year 900. Japan designated it a National Historic Site on February 13, 2018.

A Temple Beside the Mimi River

The ruins sit at roughly 23 to 25 metres above sea level, on the left bank of the lower Mimi River as it runs north toward Wakasa Bay. This stretch of valley was busy long before the temple appeared. River terraces and natural levees here carry an unusually dense run of sites from the late Kofun period into the Heian period, one of the thickest concentrations in eastern Wakasa. Excavators even found traces of a large post-built structure dating to the early 6th century, evidence that local chiefs held this ground generations before any temple was planned.

The site first drew attention by accident. In the early Shōwa era, construction of a prefectural horticultural experiment station just to the west turned up quantities of roof tile, including pieces whose concave faces still bore the imprint of cloth used in their making. Scholars took note: ancient roof tile is scarce in Wakasa, and the find marked this as something worth returning to.

Serious investigation came later. Faced with rising development pressure around the site from the late 1990s, the Mihama Board of Education began digging to define what lay beneath the fields. Continuous excavation from the 2002 season onward, eventually running to thirteen separate campaigns, brought the temple back into view.

Why It Became a National Historic Site

The founders were almost certainly a powerful clan of Mikata District in Wakasa Province. The late 7th century was a moment when district-level families across Japan took up temple building in earnest, encouraged by a central government that saw Buddhism as a way to secure the realm. In the Hokuriku region along the Japan Sea coast, though, confirmed temple sites from this early date are rare. Kōdōji is one of the few whose physical reality has actually been pinned down.

Two finds tie the temple directly to the people who built it. Excavators recovered fragments of clay sculpture, including the small spiral curls that once covered a Buddha's head. These were the first such pieces found anywhere in Fukui, and they show that the main image enshrined here was a clay figure of a Nyorai, an enlightened Buddha. They also lifted a piece of grey Sue stoneware inked with the single character "Mimi." That name points to the Mimiwake clan, the family that governed the Mimi River basin, and gives the temple a likely patron with a name.

The case for protection rested on a second point as well. Because the dig traced the complex through every stage of its life, the site offers a rare window into how a provincial clan temple was conceived, expanded, rebuilt, and finally let go. That full sequence, more than any single object, is what earned national recognition.

What to Look For

The temple followed what specialists call the Hokki-ji layout, named for a temple in Nara. It faced south, with the main hall set to the west and the pagoda to the east, the lecture hall behind them to the north, and a middle gate and south gate aligned in front. A boundary ditch fixed the precinct at about 118 metres north to south along its western edge and roughly 80 metres east to west.

Walk the plan in your mind and the building campaigns separate out. The first hall and pagoda went up between the late 7th and early 8th centuries. That earliest main hall measured about 16.8 by 13.8 metres; the first pagoda was around 12 metres on a side. The lecture hall followed in the mid-8th century, roughly 18 by 12 metres.

Then the temple grew. Sometime before the late 8th century the pagoda was torn down and rebuilt larger, now about 15.3 metres on a side, and the holes where its foundation stones were later pried out, including the deep socket for the central pillar, are still legible in the ground. Between the late 8th and late 9th centuries the main hall too was rebuilt, slightly enlarged to about 16.8 by 14.1 metres and faced with rough fieldstone masonry, with stairways added on its north and south sides. The middle and south gates belong to this same final phase. Old coins found in the fill beside the middle gate, the Mannen Tsūhō and Jingū Kaihō issues, helped date that work to the late 8th century.

None of this is dramatic to the eye. The reward here is interpretive: standing in an open field and understanding that the bumps and edges underfoot record two hundred years of one community's devotion, rebuilt and rebuilt again.

Visiting, and Where the Finds Live

The ruins themselves are open ground in the Kōdōji district, largely returned to farmland, so the things worth seeing up close are kept indoors. The tiles, the clay Buddha curls, the inscribed stoneware, and the story of the excavations are presented at the Mihama Town History and Culture Museum, which holds the displays on the Kōdōji site.

The museum stands at Kawaraichi 8-8 in Mihama and opens from 9:00 to 17:00, with last entry to the exhibition room at 16:30. It closes on Mondays, on the day following a public holiday, and over the New Year period from December 29 to January 3. Admission runs ¥100 for adults and ¥50 for elementary and junior high school students, with preschoolers free. By car it is about five minutes from the Wakasa-Mihama interchange on the Maizuru-Wakasa Expressway.

Mihama rewards a longer stay. The Mikata Five Lakes spread just to the south, five connected lakes that differ in depth and salinity and so take on visibly different shades of blue and green, best seen from the Rainbow Line ridge road. Closer to the ruins, Mimi Shrine honours Murohiko-no-ōkimi, remembered as an ancestor of the very Mimiwake clan linked to the temple, which makes a short visit there a fitting companion to the site. History-minded travellers can also climb to Kuniyoshi Castle, a mountain stronghold that held off repeated sieges in the 16th century, with its finds shown at a dedicated museum at the foot of the hill.