Mitsujo Kofun

Mitsujo Kofun: A 1,500-Year-Old Royal Tomb in the Heart of Hiroshima's Sake Country

Hidden in plain sight among the residential streets of Higashihiroshima City stands one of western Japan's most striking archaeological wonders. Mitsujo Kofun (三ツ城古墳) is a cluster of three ancient burial mounds built more than fifteen centuries ago, when the rulers of what is now Hiroshima Prefecture commanded vast manpower and resources to build monuments worthy of the dead. Unlike many ancient tombs that lie buried beneath forest growth or modern development, Mitsujo Kofun has been meticulously restored to its original 5th-century appearance. Today visitors can walk the same terraced slopes that were laid out by hand around 1,500 years ago, surrounded by 1,800 reconstructed clay figures called haniwa, and gaze across the Saijo Basin from the summit of a king's grave.

For travelers seeking something beyond Japan's famous shrines and castles, this lovingly preserved monument offers a rare and tangible window into the Kofun period (古墳時代), the formative age when the Japanese archipelago was being unified by powerful regional chieftains under the influence of the Yamato court. The site is located within easy reach of Saijo's celebrated sake brewery district, making it a natural stop on any journey through Hiroshima's lesser-known cultural treasures.

The History Behind the Mounds

The Kofun period takes its name from the very type of monument visitors encounter at Mitsujo. Between roughly the 3rd and 7th centuries, powerful clans across Japan built enormous earthen tombs to honor their leaders, and the keyhole-shaped mound (前方後円墳, zenpō-kōen-fun) became the signature form reserved for the highest-ranking chieftains. These constructions were not merely graves; they were public declarations of political authority, sacred geography, and connection to the emerging Yamato polity centered in present-day Nara and Osaka.

Mitsujo Kofun was constructed in the early 5th century, during the middle phase of the Kofun period. Although the names of those buried here have been lost to time, archaeologists believe the largest mound housed the ruler of the ancient province of Aki (安芸国), which corresponds roughly to modern western Hiroshima. Some scholars have linked this figure to the Aki-no-kuni-no-miyatsuko, a regional governor mentioned in the early historical text Sendai Kuji Hongi. Whoever the occupant, the scale and design of the tomb show clearly that this leader maintained close ties with the Yamato court, even as he or she was buried in a regionally distinctive style of stone coffin rather than the elite forms used in central Japan.

Rediscovery and Restoration

For centuries the largest mound was mistaken for the ruins of a medieval castle, which is reflected in the place name "Mitsujo" itself, meaning "three castles." It was not until 1951 that the first formal excavation, led by archaeologist Hisakazu Matsuzaki, revealed the true nature of the site and effectively launched the postwar study of ancient tombs in Hiroshima Prefecture. Further excavations took place between 1987 and 1991, uncovering rich grave goods and providing the detailed evidence needed for an unusually faithful reconstruction. From 1990 to 1993, a major restoration project rebuilt the terraced slopes, replaced the cladding stones, and reproduced the haniwa to bring the kofun back to its original appearance, opening to the public in 1994.

Why Mitsujo Kofun Was Designated a National Historic Site

On June 3, 1982, the Japanese government designated Mitsujo Kofun a National Historic Site (国指定史跡), and an additional area was added to the protection zone in January 2001. The reasons behind this designation reflect both the monument's intrinsic importance and what it reveals about ancient society.

First, the largest mound, known as No. 1, is the largest keyhole-shaped tomb in Hiroshima Prefecture, with a total length of about 92 meters, a circular rear section roughly 62 meters in diameter and 13 meters tall, and a square front section about 66 meters wide. Its three-tiered terraced design closely mirrors the construction techniques used for the great royal tombs of the Yamato kings, demonstrating that the chieftains of Aki were participating in a shared elite culture that stretched from Kyushu to the Kanto region.

Second, the burial chambers themselves are remarkable. Three box-shaped stone coffins were laid out on top of the rear circular mound, and two of them feature an unusual double structure in which the coffin is enclosed by a second stone chamber with its own lid. This design is rare in Japan and gives Mitsujo a unique place in the study of ancient burial customs. The grave goods recovered from these chambers include a bronze mirror, dozens of beads of various materials, iron swords and short blades, an iron spear, eighty iron arrowheads, a bronze bracelet, and bone combs, all attesting to the wealth and status of the deceased.

Third, the sheer quantity and variety of haniwa, the hollow ceramic figures arranged on the slopes, is unparalleled in the prefecture. About 1,800 haniwa once ringed the mound, including cylindrical and morning-glory-shaped pieces as well as figurative examples in the form of houses, shields, quivers, helmets, armor, ceremonial parasols, chickens, waterfowl, and horses. Together they paint a vivid picture of how 5th-century Japanese imagined the afterlife and the symbolic court that should accompany a great leader into eternity.

Highlights for Visitors

What sets Mitsujo Kofun apart from many other ancient tombs in Japan is the quality of its restoration. While most kofun across the country survive only as tree-covered hills, Mitsujo has been carefully rebuilt so that visitors can experience the monument as it would have looked when it was new. The result is genuinely transporting.

The Reconstructed Mound and Haniwa Field

The slopes of the No. 1 mound are clad in approximately 75,000 small stones, a feature known in Japanese as fukiishi, which originally served both decorative and structural purposes. Encircling each of the three terraces are rows of cylindrical haniwa packed almost shoulder to shoulder, creating an effect that is as visually arresting today as it must have been in the 5th century. Pathways and stairways allow visitors to climb to the top, walk along the connecting saddle between the front and rear sections, and view the mound from many angles.

Glass-Covered Burial Chambers

One of the most memorable features for visitors is the ability to look directly down into the burial chambers themselves. Glass panels installed over the three stone coffins on top of the rear mound allow you to see the interiors where the chieftain and his attendants were laid to rest. It is a striking and humbling experience to stand on top of an ancient tomb and look into spaces that were sealed for fifteen centuries.

Mound No. 2 and the Mysterious Echo

Adjacent to the keyhole mound is the smaller round Mound No. 2, about 25 meters in diameter and 4 meters tall. Local guides will tell you that if you clap your hands while standing on a particular spot on its steps, you will hear an unusual echo, a quirk that has charmed generations of visitors. Mound No. 3, an even smaller earthwork, completes the group.

Exhibit Spaces

The original burial goods and a selection of excavated haniwa are displayed in the guidance corner of the Higashihiroshima City Central Library, just east of the park. A second exhibition room inside the park's management building houses replica haniwa, explanatory panels, and miniature models showing how the mound was constructed. Volunteer guides from the local history society are sometimes available to walk visitors through the displays.

What to See and Do Nearby

Mitsujo Kofun stands within Saijo, the historic central district of Higashihiroshima City, which is one of Japan's three great sake-brewing towns. After exploring the kofun, visitors can stroll along the Sakagura-dori, a short street lined with about a half dozen working sake breweries marked by their distinctive red brick chimneys and white plaster walls. Many of the breweries offer tastings and shop sales of their seasonal products. The Saijo sake district is concentrated around Saijo Station, only a short bus ride from the kofun.

The Higashihiroshima City Central Library, immediately east of the park, is also home to a sizable collection of materials on local history and is a comfortable stop in any weather. For families, the Mitsujo Neighborhood Park surrounding the kofun includes playgrounds with slides and climbing structures, making it a favorite outing spot for residents. Slightly farther afield, the campus of Hiroshima University, just south along Boulevard Avenue, offers wide open green spaces, while the Saijo Inari Shrine and the Mitsuo Shrine give a glimpse into the area's other historic spiritual traditions.