Mirokuji Government Office Ruins / Mirokuji Government

Mirokuji Kanga Site Group: Six Centuries of Ancient Mino on a Single River Terrace

Where the Nagara River breaks out of the Oze Gorge and begins to widen toward the Nōbi Plain, a low terrace at Ikejiri in Seki City carries the layered footings of six centuries of ancient Mino. Within a few hundred metres lie the foundation stones of a Buddhist temple built in the late seventh century, the post-hole traces of an eighth-to-tenth-century district government office, the kiln complex three kilometres away that fired its roof tiles, and a stone-chambered burial mound older than any of them. The Mirokuji Kanga Site Group is the national designation that gathers these four components — Mirokuji Kanga Ruins, Mirokuji Temple Ruins, Maruyama Old Kiln Ruins, and Ikejiri Ōtsuka Tumulus — into a single Historic Site (shiseki).

Today the central area is open to the public as Mirokuji Historic Park (Mirokuji Shiseki Kōen). The buried foundations have been sealed in the earth for protection, and their footprints are shown on the surface in gravel and replica timber pillars, so a visitor walks the actual outlines of the seventh-century pagoda and the eighth-century government hall.

The Muge Clan and the Layers Beneath the Surface

The history of this place is in essence the history of one local family. The Muge (also written Mugetsu, Muge-tsu, Mibu, and several other ways in the early chronicles) were a regional gōzoku, a powerful clan tied to the Yamato court through military and ritual service. Their decisive moment came in 672, during the Jinshin War. A clansman named Mugetsu no Kimihiro served as an attendant (toneri) to Prince Ōama and fought on the winning side. After Ōama took the throne as Emperor Tenmu, the Muge were rewarded with formal authority over Mugi District (now Seki and Mino).

That reward is what every later layer of the site grew out of. Around the turn of the seventh century the clan built a square tumulus, the Ikejiri Ōtsuka, on the western edge of the terrace. Within a few decades of the Jinshin War their descendants commissioned a full Buddhist temple, Mirokuji, on the same terrace. As the ritsuryō state organised the provinces under the Taihō Code, the family's residential compound east of the temple was rebuilt into the formal seat of the district administration, the gunga. Excavations show that the post-and-beam halls of the clan's stronghold were demolished and replaced in the early eighth century by an orderly compound of administrative and storage buildings on a new alignment. A few generations of one family is visible in the dirt, transitioning from local lords to officers of the imperial state.

Why This Site Is a National Historic Site

The site was first designated in 1959 (Shōwa 34), at that point only as the temple ruin plus the Maruyama kiln site that supplied its tiles. The far more consequential discoveries came later. Between 1994 and 2005, eight seasons of rescue excavation at the field east of the temple uncovered something archaeologists had not expected: a complete gunga in plan. The district office had a walled administrative compound of about 50 by 60 metres, with a main hall and two flanking halls arranged in the hin (品) character pattern. Until this find, that "品" arrangement had only been confirmed at provincial-level government seats (kokufu); seeing it at a humble district office overturned the prevailing model of how the Nara state organised its provinces. Slightly to the south stood a storehouse precinct (shōsō-in) of roughly 130 by 40 metres, with at least nine raised granaries in its earlier phase. Carbonised rice excavated from the storehouse footings is direct evidence of the rice tax (so) that the district collected and shipped on to the capital.

In 2007 these findings were added to the national designation and the site was renamed the Mirokuji Kanga Site Group. The final addition came in 2016, when the Ikejiri Ōtsuka Tumulus joined the listing. Nationally, only one comparable site — the Hara Kanga Site Group in Saitama Prefecture — preserves a Buddhist temple, district office, ritual site, and associated burial complex functioning together within a single archaeological landscape. That is the case the Agency for Cultural Affairs makes for the value of this place: an entire regional administration, with all its supporting institutions, can be read at one location.

Walking the Park: What to Look For

The visitor's experience falls into three parts that can comfortably be walked in a morning.

At the temple ruin (Mirokuji-ato), the layout is in the Hōki-ji style, with pagoda and golden hall standing side by side rather than on a single axis. The pagoda's earthen platform is roughly eleven metres square, with the central foundation stone (shinso) still in place along with four side-pillar stones. To its west sits the kondō platform, about fifteen by eleven metres, the surviving stones suggesting a 5-by-4-bay building. The lecture hall, sutra repository, bell tower, corridor, central gate, and south gate have all been located. The late seventh-century date, within the Hakuhō period, comes from the style of the roof tiles, which match those produced three kilometres northeast at Maruyama.

The reconstructed government compound is the centrepiece of the park. The "品" arrangement of the main hall and two flanking halls is laid out in gravel and squared timber posts; standing in the centre of the courtyard gives a clearer sense of the institution's scale than any explanatory panel can. Beside it, the long rectangle of the storehouse precinct shows the bases of the granaries that once held the district's rice. Information boards explain the two main rebuilding phases, including the shift from earthfast posts to stone-based pillars and the gradual enlargement of the storage capacity.

A short walk west brings you to the Ikejiri Ōtsuka Tumulus. Its earth mound has long since eroded away, leaving the massive stones of the corridor-style burial chamber exposed. Locally it is called the Ishibutai of Mino, in deliberate echo of the famous Asuka tomb. The corridor (sendō) runs 10.29 metres deep, opening into a burial chamber 4.32 metres long, 2.66 metres wide, and 2.5 metres high, with a floor of river-cobble paving. Excavations in 2008 and 2011 dated the construction to the early seventh century and recovered a small Haji-ware jar, a Sue-ware lid, and iron fittings clad in gilt bronze — the kind of grave goods that point to a district-level chieftain. The tomb is generally accepted as the resting place of a Muge ancestor, the figure whose descendants would build the temple and govern the district from the buildings just downhill.

The Monk Enkū's Last Years

The story of the site does not end with the Heian period. By the seventeenth century the temple had long since fallen out of use, the buildings gone, the foundation stones overgrown. In about 1689 (Genroku 2), the itinerant Buddhist sculptor Enkū settled here. Born in Mino Province in 1632, he had spent his adult life travelling between Hokkaidō and the Kinai, carving rough, vigorous Buddhist images from local wood, some five thousand of which still survive across Japan. Enkū restored the ruined Mirokuji as a personal hermitage, and used it as his base until his death on the riverbank in 1695. His tomb (nyūjō-zuka) and grave stand a short walk from the temple foundations, and roughly forty of his statues are kept and exhibited at the Seki City Enkū Museum (Enkū-kan) on site.

The museum also displays the principal excavated objects from the digs: roof tiles from the temple, the inkstones and ink-inscribed pottery (some pieces marked with the character for "great temple", ōdera) recovered from the western ritual site, and a sample of the carbonised rice from the storehouse precinct.

Surroundings and Related Sites

The Nagara River at the foot of the terrace is one of Japan's three clearest large rivers and the setting for Oze Ukai, a traditional cormorant-fishing technique held annually from 11 May to 15 October. The technique itself is registered as an Important Intangible Folk Cultural Property. Evening boats put out from the Ayunose-bashi bridge just below the site.

The Maruyama Old Kiln Ruins, the fourth component of the designation, sit on an isolated hill about three kilometres to the northeast in Ōyada, Mino City. Four climbing kilns (noborigama) were investigated there in 1957 by a Nagoya University team led by Sumida Shōichi and Narasaki Akiichi. One kiln preserves a 9.3-metre-long firing chamber with its firebox and flue intact and parts of the vault still in place. The site is not maintained as a visitor attraction in the way the temple park is, so those who want to see the kiln-temple link are better served by the displays at the Enkū Museum.

Mino City itself, about twenty minutes away by car, repays a half day's detour. It is the home of Mino washi, one of the three classical Japanese papers and a UNESCO-recognised craft, and its preserved Udatsu Townscape of merchant houses with distinctive fire-break walls is a designated Important Preservation District for Groups of Traditional Buildings.