Before the Fighters Build in Eniwa, Archaeologists Are Reading the Ground

In Nishi-Shimamatsu, Eniwa, two kinds of survey are now happening on the same ground. Engineers are measuring the land for a future urban district. Archaeologists are opening the soil to find out who used it long before a professional baseball development was imagined.

The roughly 46-hectare planning area between Megumino and Shimamatsu stations includes the intended relocation area for the Hokkaido Nippon-Ham Fighters’ farm facilities. Eniwa City began boundary, topographic and buried-cultural-property work in September 2026. The archaeology program includes machine removal of topsoil where appropriate, hand excavation, detection of features and recovery of artifacts. ^[1]

There was already a reason to look. UHB Hokkaido Cultural Broadcasting reported on September 16, citing the Eniwa Board of Education, that a preliminary survey in July 2025 had uncovered Jōmon-period pottery and stone tools. The active 2026 excavation was opened to media that day. ^[2]

Forty-six hectares of future development — and an archaeological question underneath

Eniwa’s new urban-district planning area covers about 46 hectares between two JR Chitose Line stations. The city is conducting cadastral and topographic surveys to define boundaries, area and elevation, including drone survey work, while archaeological specialists establish the presence, extent and character of buried cultural properties. ^[1]

Much of the land is still privately owned farmland. After the Fighters relocation area was announced in July, Eniwa issued an unusual public warning after unauthorized entry onto private fields and unsafe roadside photography. ^[5]

Why the Fighters want to bring player development back to Hokkaido

The club’s current farm home, Fighters Kamagaya Stadium in Chiba Prefecture, opened in 1997 after the farm operation moved from a Tama River training ground in Kawasaki. For nearly three decades it has served as the organization’s player-development base. The Fighters have repeatedly described scouting and development as central to the club’s identity. ^{[12] [13]}

The first team moved to Hokkaido in 2004 and, in 2023, into ES CON FIELD HOKKAIDO at Hokkaido Ballpark F Village in Kitahiroshima. The farm operation, however, remained in the Tokyo metropolitan region.

In July 2025, the Fighters formally announced their intention to relocate the farm operation to Hokkaido under the project name ONE BASE HOKKAIDO. Chief Baseball Officer Hideki Kuriyama described a broader development center focused not only on baseball skills but on conditioning, physical development and preparing people capable of competing globally. ^[4]

On July 2, 2026, the club selected Eniwa for the relocation. Kuriyama said he wanted a place where people from around the world could gather, where players could truly develop and where children could eventually go out into the world. The club says it is aiming to open the new facilities in 2030 or 2031. ^[3]

But Nishi-Shimamatsu was never empty ground

The archaeological interest begins with the name itself. Nishi-Shimamatsu is already a major place in the archaeology of central Hokkaido.

At the Nishi-Shimamatsu 5 site, river-improvement and flood-storage construction led to the excavation of 21,210 square meters between fiscal 2000 and fiscal 2004. The work recovered about 1.67 million items spanning multiple periods, including Jōmon pottery, stone tools and lacquer objects, as well as metal artifacts from much later centuries. ^[6]

Late and Final Jōmon graves dating to around 3,000 years ago contained lacquered combs, beads and other ornaments. Eniwa archaeology from this period is unusually rich in sophisticated lacquerwork, with major finds also known from Karinba and Kashiwagi B. ^{[8] [9]}

And lacquerworking in Eniwa goes back farther still. The city’s archaeological chronology identifies the Nishi-Shimamatsu 3 site as yielding Eniwa’s oldest known lacquer product, from the Early Jōmon period around 6,000 years ago. ^[9]

Karinba: a road project that uncovered one of Eniwa’s great Jōmon cemeteries

Eniwa’s best-known archaeological site lies elsewhere in the city: Karinba. In 1999, excavation ahead of a municipal road project uncovered a cemetery dating to the end of the Late Jōmon, about 3,000 years ago. Several large collective graves contained multiple individuals accompanied by lacquered combs, bracelets, belt ornaments and large numbers of beads. ^[8]

Karinba was designated a National Historic Site in 2005; 397 objects from the burials became Important Cultural Properties in 2006. Modern construction did not simply threaten the archaeology. The requirement to investigate before building is what brought the site to public attention. ^{[7] [8]}

Nishi-Shimamatsu 5 also tells a much later story

The site is important not only for Jōmon material. Excavators identified 84 pit graves dating mainly to the seventh and eighth centuries and six ditched graves from roughly the eighth to ninth centuries. More than 170 metal objects were buried with the dead, including swords, knives, arrowheads and axes. Eniwa says the metal was made outside Hokkaido. ^[6]

In August 2024, 218 objects from this later burial complex — 62 ceramic pieces, 155 metal objects and one amber bead — were designated Important Cultural Properties. Eniwa describes the collection as exceptional evidence for links between the Ishikari lowland, northern Tohoku and the political-cultural world of the ancient Japanese state. ^{[7] [10]}

Nishi-Shimamatsu, then, is not a single-period “Jōmon place.” The archaeological landscape preserves repeated human use across thousands of years, including Jōmon, post-Jōmon and Satsumon-period histories.

What do the 2025 pottery and stone tools actually tell us?

For now, less than the headline might suggest.

UHB’s September 16 report confirms only that the Eniwa Board of Education said Jōmon pottery and stone tools were found during preliminary work in July 2025. Public material does not yet give an artifact count, ceramic style, stone type, precise age, feature association or coordinates. ^[2]

That means the finds cannot responsibly be assigned to the same period as the 3,000-year-old Karinba graves or the lacquer-rich phase of Nishi-Shimamatsu 5. “Jōmon” in Hokkaido spans millennia. Eniwa’s own archaeological chronology contains sites from the earliest pottery periods through Early, Middle, Late and Final Jōmon. ^[9]

What matters in archaeology is not only the object but context: which soil layer it came from, whether artifacts occur with hearths, postholes, pits, burials or former stream channels, and how concentrations relate spatially. A plain fragment of pottery in a secure feature can sometimes tell more about human activity than an isolated spectacular object.

Excavation is part of development procedure, not an archaeological ambush

Japan has roughly 460,000 known buried-cultural-property areas, according to the Agency for Cultural Affairs, and around 9,000 archaeological excavations are conducted each year. Under the Cultural Properties Protection Act, development in known archaeological areas requires advance procedures; where a site cannot be preserved in place, excavation and documentation may be required before construction so that a record survives. ^[11]

Eniwa describes the current work in similar terms: an essential process for understanding and protecting historical heritage before the new district is built. ^[1]

The outcome does not automatically mean construction stops. Depending on the significance, extent and preservation of features, authorities and developers can adjust plans, preserve archaeology in place or carry out record-preservation excavation. As of September 16, Eniwa has not announced that the archaeology changes the Fighters’ target opening period.

Two ideas of “development” meet on the same ground

The Fighters’ project is built around development in the sporting sense: training players, improving conditioning and building a place meant to produce future talent. ^{[3] [4]}

Before that future center is built, Eniwa is studying another kind of human development — the settlement, technology, burial practice and movement of people who used the same landscape thousands of years earlier.

Karinba came to light because of a road project. Nishi-Shimamatsu 5 was extensively documented because of river engineering. In 2026, plans for a baseball facility and a new urban district are once again creating the opportunity, and the obligation, to read what lies below.

If young Fighters someday train here, they may be running above ground where Jōmon people once left pottery and stone tools. In Eniwa, building the next place has repeatedly revealed the places that came before it.