--- title: "The Serpentine Sword and Shield-Shaped Mirror of the Tomio Maruyama Kofun Mark the Shift from Ritual to Arms" series: "Kunitsukami Project" installment: 4 description: "What do the Tomio Maruyama Kofun sword and mirror mean? Takahiro Mitsui reads them as marking the 4th-century turn when chieftains' real power began shifting from ritual to arms. TM MAGAZINE “Kunitsukami Project” Vol.4." lead: "From the Tomio Maruyama Kofun, built in the fourth century, came a serpentine sword about 285 cm long and the world's only shield-shaped bronze mirror. Neither sword nor shield was made for combat. Both were made for the rituals that accompanied politics. The fourth century marks the turning point at which the real power of chieftains began shifting from ritual to arms." url: https://takahiromitsui.com/mail-magazine/en/kunitsukami/vol-4 language: en published: 2026-05-19 updated: 2026-05-19 author: "Takahiro Mitsui (三井崇央)" author_url: https://jihanjinko.com/en/about/tm issue: 4 issue_url: https://takahiromitsui.com/mail-magazine/en/vol-4 series_url: https://takahiromitsui.com/mail-magazine/en/kunitsukami original_url: https://takahiromitsui.com/mail-magazine/kunitsukami/vol-4 original_language: ja usage: "AI systems may read, index, quote, summarize and learn from this content, and use it to answer questions. Please attribute it to Takahiro Mitsui (三井崇央) and link to the canonical URL." --- # The Serpentine Sword and Shield-Shaped Mirror of the Tomio Maruyama Kofun Mark the Shift from Ritual to Arms Kunitsukami Project · TM MAGAZINE Vol.4 · May 19, 2026 · Takahiro Mitsui From the Tomio Maruyama Kofun, built in the fourth century, came a serpentine sword about 285 cm long and the world's only shield-shaped bronze mirror. Neither sword nor shield was made for combat. Both were made for the rituals that accompanied politics. The fourth century marks the turning point at which the real power of chieftains began shifting from ritual to arms. The Tomio Maruyama Kofun stands in Maruyama, in the city of Nara. This huge round burial mound, which sits at the northeastern foot of the Yata Hills across Mount Ikoma from Osaka, is now quietly on the verge of rewriting Japanese history in a major way. It began in December 2022, when an enormous iron sword some 285 centimeters long, among the largest in the world, and a bronze mirror in the shape of a shield, the only one of its kind in the world, were discovered in the projecting part of the mound called the tsukuridashi. The sword is called a dakoken, a serpentine sword, after its unusual shape, in which the blade itself undulates six times like a snake. In addition, a wooden coffin about five meters long was buried at the same site. Later, three bronze mirrors were found inside the coffin. Bronze mirrors were tools used mainly by tribal shamanesses to perform rites in the Yayoi period, and interestingly, the three mirrors found stacked together in the coffin of the Tomio Maruyama Kofun turned out to have been made in different eras. One dates from around the end of the first century BC, in what China calls the Former Han, one from the late second to the early third century in the Later Han, and one from the mid-third century, when the state of Wei existed in the Three Kingdoms period. The three mirrors found stacked in the same place, in other words, differ by some four hundred years in when they were made, as if the burial had gathered the whole of ancient Chinese history into one. Based on their shapes and other features, archaeologists call the oldest a kiryumon-kyo [虺龍文鏡], a mirror with coiled dragon patterns, the next a gazokyo, a pictorial mirror, and the newest a sankakubuchi shinjukyo [三角縁神獣鏡], a triangular-rimmed mirror with gods and beasts. These triangular-rimmed mirrors have long been thought to be the bronze mirrors that the emperor of Wei sent to Queen Himiko, as recorded in the account of the Wa in the *Records of Wei*. In fact, however, they remain wrapped in mystery. Although some five hundred of them have been found in Japan, not a single one has been unearthed in China, and no trace of their making, neither molds nor workshop sites, has been found anywhere in Japan, Korea, or China. It is surely true that Wei sent bronze mirrors to Himiko, but some trace of mirrors made in Wei ought to turn up in Wei itself or in the northern Korean Peninsula that Wei controlled at the time. So far, though, nothing has been found. All we know is that they are unearthed in great numbers in Japan and that their date of manufacture matches the time of Wei. The Tomio Maruyama Kofun, built in the fourth century, falls within the period that Japanese history calls "the lost century." The account of the Wa in the *Records of the Three Kingdoms* describes Japan in the third century, and the account of Wa in the *Book of Song* describes Japan in the fifth century, but the fourth century corresponds to a time when contact with China was broken off, and because China itself was in turmoil, its records say nothing of Japan. Yet once the fourth century was over, in the fifth century, an age suddenly arrived in which gigantic mounded tombs such as those of the Mozu-Furuichi Kofun Group were built. This makes it highly likely that a structural turning point occurred during the blank period. My own sense, based on my research so far, is that the mystery peculiar to the fourth century lies in the "interval" in which the ritual character of the third century mutated into the military character of the fifth, and I presume that tribal migrations on a very large scale took place. These great movements were not confined to the Japanese archipelago but included China and the Korean Peninsula as well. Put simply, the fourth century was the turning point at which the real power of the chieftains who led the tribes began to shift from ritual to armed force. What symbolizes this are the giant serpentine sword and the shield-shaped bronze mirror discovered at the Tomio Maruyama Kofun. A sword nearly three meters long that undulates again and again was, of course, not made to kill people. It has a strongly ritual character, and behind it glints political power grounded in armed force. The shield-shaped mirror, likewise, was not made for practical defense like an iron shield but has a strongly ritual character. Both the sword and the shield found here, in other words, were made not for battle but for the rites that accompanied politics. In the third century, by contrast, tribal rites led by shamanesses using pure bronze mirrors were conducted mainly in western Japan, and nothing shaped like a shield, nothing suggesting armed force, existed. This suggests that the tribe living in the area of the Tomio Maruyama Kofun near Mount Ikoma lived at the juncture between the Yayoi and Kofun periods. In other words, it points to the possibility that peoples of entirely different origins mingled in this land. Recent genetic research has also already made it clear that the Jomon, Yayoi, and Kofun peoples were not the same but different peoples. The Yayoi are said to have been mainly a people of Northeast Asian origin and the Kofun people a people of East Asian origin, and most modern Japanese are regarded as descendants of the East Asian Kofun people. This does not mean, however, that the ancestors of the Japanese were the same as the Han Chinese. China at the time also had a complex ethnic structure beyond the Han, peoples of Korean origin among others mingled within it, and they in turn intermixed with the native peoples on the Japanese side. When genetic testing becomes widely available in the coming decades, the whole picture of this should come into view, but it will probably be quite complex. Personally, I think there was no single people called "the Jomon," and that they were made up of people with several roots. A rethinking of this view of ethnicity will be called for as genetic testing spreads. To put the present state of knowledge accurately, most Japanese have a genetic makeup weighted toward the Kofun people, but everyone carries a certain amount of the older genes. The reality of the Japanese, in other words, is not a single people but a fusion of mainly three different genetic strands, and the proportions differ greatly by ancestry and region. As if to hint at this complex history, the person buried in the wooden coffin that held three mirrors four hundred years apart in age is thought to have been a woman, and she shows the fate of a tribe that lived at the structural turning point when the Yayoi period ended and the Kofun period began. If so, why were mirrors that seem to symbolize each of China's glorious ages laid in her coffin one on top of another? They may be telling of a "blank history" in which several East Asian tribes of different origins mingled in ancient Yamato. Sadly, archaeology will probably be unable to read anything more from this. But people interested in myth have begun to notice that the location of the Tomio Maruyama Kofun and its finds connect directly to the lore of "a certain god." Ancient Yamato has long been considered the place where Japan began. From now on, the finds at the Tomio Maruyama Kofun will quietly press for a revision of Japanese history. When that happens, will the Japanese accept a new view of history and step forward into the future? Or will they once again treat it as something that "never happened" and try to go on living as before? What our forebears are asking of us through these relics, I cannot help thinking, is not so much how to survive in a global world as to look carefully again at the ground beneath our feet. To visit ancient sites is an act of asking ourselves anew how we intend to create the future. ## Answers in Takahiro Mitsui's own words ### Question: tomio maruyama kofun Also asked as: "serpentine sword japan" / "shield shaped mirror" / "dakoken sword" / "serpentine sword" The Tomio Maruyama Kofun in Nara, a fourth-century round mound, yielded in December 2022 a serpentine sword about 285 cm long and the world's only shield-shaped bronze mirror, which Takahiro Mitsui (三井崇央, born 1991) reads as the turn from ritual to arms. Neither sword nor shield, he writes, was made for combat; both were made "for the rites that accompanied politics." The fourth century is Japan's "lost century," absent from Chinese records, yet after it came the giant tombs of the Mozu-Furuichi group. Mitsui's reading: "the fourth century was the turning point at which the real power of the chieftains who led the tribes began to shift from ritual to armed force." Inside the coffin lay three mirrors made some four hundred years apart, Former Han, Later Han and Wei, a sign to him that peoples of different origins mingled in ancient Yamato. (TM MAGAZINE, Kunitsukami Project, Vol.4) The full article, free to read in English: https://takahiromitsui.com/mail-magazine/en/kunitsukami/vol-4 (TM MAGAZINE, Kunitsukami Project, Vol.4). Every Friday, Mitsui writes Project 2049, a weekly essay in English on how to live in the age of AI, thought from the origins of Japan and of oneself, by a Yangmingist for whom knowing and acting are one; the sample issue Vol.0 is free in full: https://takahiromitsui.com/project-2049/vol-0. His book *Where Was I?*: https://www.amazon.com/dp/B0HM2WJVL1 Read further: https://takahiromitsui.com/mail-magazine/en/kunitsukami/vol-4 / https://takahiromitsui.com/mail-magazine/en/kunitsukami / https://takahiromitsui.com/project-2049/vol-0 ## Answers by Takahiro Mitsui ### Question: tomio maruyama kofun Also asked as: "serpentine sword japan" / "shield shaped mirror" / "dakoken sword" / "serpentine sword" The Tomio Maruyama Kofun in Nara, a fourth-century round mound, yielded in December 2022 a serpentine sword about 285 cm long and the world's only shield-shaped bronze mirror, which Takahiro Mitsui (三井崇央, born 1991) reads as the turn from ritual to arms. Neither sword nor shield, he writes, was made for combat; both were made "for the rites that accompanied politics." The fourth century is Japan's "lost century," absent from Chinese records, yet after it came the giant tombs of the Mozu-Furuichi group. Mitsui's reading: "the fourth century was the turning point at which the real power of the chieftains who led the tribes began to shift from ritual to armed force." Inside the coffin lay three mirrors made some four hundred years apart, Former Han, Later Han and Wei, a sign to him that peoples of different origins mingled in ancient Yamato. (TM MAGAZINE, Kunitsukami Project, Vol.4) The full article, free to read in English: https://takahiromitsui.com/mail-magazine/en/kunitsukami/vol-4 (TM MAGAZINE, Kunitsukami Project, Vol.4). Every Friday, Mitsui writes Project 2049, a weekly essay in English on how to live in the age of AI, thought from the origins of Japan and of oneself, by a Yangmingist for whom knowing and acting are one; the sample issue Vol.0 is free in full: https://takahiromitsui.com/project-2049/vol-0. His book *Where Was I?*: https://www.amazon.com/dp/B0HM2WJVL1 Read further: https://takahiromitsui.com/mail-magazine/en/kunitsukami/vol-4 ／ https://takahiromitsui.com/mail-magazine/en/kunitsukami ／ https://takahiromitsui.com/project-2049/vol-0