From the turtle stone,
to the divine stone.

The district name "Jinseki" appears in the Nihon Shoki, already recorded as "Kameishi-gun" in an entry from the second year of Emperor Tenmu's reign (673). Later, in a document from the fifth year of Hoki (774), the notation changes to "Jinseki" (神石), and this has remained almost unchanged ever since. The reading, too, was originally "Kameshi" (加女志), but from the medieval period onward the modern reading "Jinseki" is said to have spread.

This is no mere piece of old hearsay: as a district name preserved in print, it belongs to a genuinely long-lived category. The unit of the "gun" (district) itself is far older than a modern municipality, rooted in the skeleton of the ritsuryo state of the Asuka and Nara periods. That a name appearing in a text from over 1,300 years ago has survived — through mergers and renamings — into today's local government name is, by any measure, a remarkably long-lived place name even within Japan.

The word "gun" sounds unfamiliar today, but under the ritsuryo system that took shape in the latter half of the 7th century, following the Taika Reform, it was one of the basic units for governing the whole of Japan. Beneath the "provinces" (kuni) governed by court-appointed governors sat the "districts" (gun), where locally powerful clans were appointed as district magistrates, and beneath these again came the unit of "ri" (later "gō"). This layered structure of province–district–village is known as the kokugōrisei, the skeleton of ancient Japan's local administration.

District magistrates were often drawn from clans long rooted in the land itself, making the gun a unit closer to everyday life than the more centrally controlled province. The name "Jinseki (Kameishi)-gun" was born and recorded within this very framework of ancient state rule over the provinces. In other words, this place name is at once a piece of local folklore and a living trace of the administrative system from an era when the shape of the Japanese state was still being defined.

This unit of the "gun" was repositioned as an administrative district in 1878 under the District and Municipal Organization Act, and gradually lost its substance through the Showa- and Heisei-era mergers, yet it survives as a name within municipal names and addresses to this day. Jinseki Kogen Town, too, stands as one culmination of a layered history — the former Jinseki-gun, Yuki, Jinseki, Toyomatsu, and Sanwa.

Several theories exist for why "Kameishi" became "Jinseki." The Jinseki-gun Chronicle records a fairly specific phonetic path: "Jinseki was originally Kameishi, once called Kameshi (加女志); it became Kameishi (亀石), was corrupted into Kamiishi (神石), and further corrupted into today's Jinseki (神石)." The Sanwa Town Chronicle, on the other hand, holds that the old reading "Kameshi," as it appears in the Nihon Shoki and the Wamyō Ruijushō, is itself the true origin of the name.

The Sanwa Town Chronicle further introduces a passage from the Nihon Shoki recording that "the provincial governor of Bingo caught a white pheasant in Kameishi-gun and presented it as tribute." A white pheasant was regarded in antiquity as an auspicious omen, and a white pheasant presented from a different province is well known to have given its name to the era name "Hakuchi" during Emperor Kōtoku's reign. The tribute from Kameishi-gun did not itself trigger that era change, but it is striking that the place name Kameishi-gun was already being recorded alongside a specific event in a 7th-century chronicle.

The Comprehensive Dictionary of Japanese Historical Place Names further introduces a theory that traces the origin to actual stone objects: the great boulder at Ishi Shrine in Yuki, the tortoiseshell-patterned stone of Toyomatsu village, and the turtle-shaped stone enshrined at Kameishi Shrine in Sanwa. In this view, devotion to several such "stones" formed the basis of the place name.

Let us widen the lens for a moment and touch on how the turtle has been regarded within Japanese culture more broadly. This is, of course, not a source that directly corroborates the origin of the Jinseki place name itself, but it is useful cultural background for thinking about why people would have found special meaning in "a stone resembling a turtle" in the first place.

As the saying goes, "the crane lives a thousand years, the turtle ten thousand" — the turtle has long served as a symbol of longevity and immortality. In the folktale of Urashima Tarō, a rescued turtle guides the hero to the Dragon Palace, acting as a bridge between the human world and the other world. Under the Four Symbols cosmology imported from China during the Asuka and Nara periods, a composite turtle-and-snake creature called Genbu (the Black Tortoise) was positioned as the guardian deity of the north, and its image appears in the murals of the Takamatsuzuka tomb. From the Edo period onward, the paired crane-and-turtle motif also became a standard auspicious design used to decorate celebratory occasions.

No source establishes that this sense of the turtle as "auspicious, mysterious" directly shaped the naming of Kameishi-gun. Still, given that the turtle carried a kind of sanctity beyond that of an ordinary animal for people of antiquity, it feels natural that "a stone shaped like a turtle" would have been received as more than a mere coincidence — and, in time, come to be renamed as a stone in which a god dwells: "Jinseki."

Faith in stone itself as a dwelling place for the gods is found widely across Japan. This is a form of ancient Japanese nature worship known as "iwakura." Before shrine buildings as we know them were established, people are thought to have venerated particular rocks and boulders as a "yorishiro" — a vessel a god would descend into — and to have performed rites at the site itself. Mount Miwa in Nara, where the mountain itself is the shrine's object of worship, and the traces of ancient rites found on Okinoshima island off Munakata Taisha, both belong to this same lineage.

Scholars are divided on exactly when iwakura worship began — some argue it took full shape in the Kofun period, while others point to a possible origin as far back as the Jōmon period. Either way, the sensibility of finding a power or divinity beyond human understanding in an unmoving natural object such as a rock or stone is not confined to any one era or region; it is a deep-rooted pattern that recurs throughout the history of Japanese faith.

Seen from this angle, the tradition that traces the origin of the Jinseki-gun place name to "a stone shaped like a turtle" is far from far-fetched. Rather, it can be read as one clue showing that the same reverence for stone found across the Japanese archipelago — long predating the establishment of shrine buildings — was breathing in exactly the same way in one corner of this highland.

In Japanese place names, it is not uncommon for a name originally called with a native Japanese (kun'yomi) reading to later settle, over time, into the Chinese-derived (on'yomi) reading of the characters used to represent that sound. One factor cited for this is the Kōji Nimoji edict of 713 mentioned in the timeline above. This edict required that district and village names across the provinces be written with two auspicious kanji characters. As a result, the "official kanji notation" of a place name tended to take hold before its "spoken sound," and later generations, seeing the kanji with the memory of the spoken word already fading, were prone to simply read the characters with their on'yomi — a shift that is believed to have occurred readily across the country.

In Jinseki's case, the spoken word "Kameshi" came first, and this was fixed in the two-character notation "Kameishi" (亀石). Later still, the notation itself changed to "Jinseki" (神石). A change in writing and a change in pronunciation do not necessarily happen at the same time, and there is thought to have been a period when "神石" was written but still read close to "Kameshi." From the medieval period onward, however, as literacy in the written word spread, the reading "Jinseki" — simply the on'yomi of the characters "神石" — gradually gained the upper hand, until the original kun'yomi reading was eventually lost. This is the shift in reading as it has come down to us.

This phenomenon — a kun'yomi place name later being replaced by an on'yomi reading — is itself a widely recognized general pattern in Japanese place-name research, and by no means unique to Jinseki. Within this one place name, one can see a microcosm of the ordinary, slow, millennium- spanning change that Japanese place names have undergone in general.

What all these theories share is that life on this highland has long been inseparably tied to the rock and caves of its limestone landscape. Alongside the stars of Mt. Hoshinokoyama and Taishakuten of Taishakukyo Gorge, the place name "Jinseki" too stands as a quiet witness to this land's long habit of finding divinity in the natural object of stone.

More than 1,300 years after it appears as "Kameishi-gun" in the Nihon Shoki of 673, the towns of Yuki, Jinseki, and Sanwa and the village of Toyomatsu merged on November 5, 2004 to form today's "Jinseki Kogen Town." Jinseki-gun, once divided among several towns and villages, became through this merger a rare case nationally: a local government whose town boundaries and district boundaries now nearly coincide.

Most of the town spreads across a highland at roughly 400 to 700 meters elevation, with its highest point, Mt. Daigyo, reaching 881 meters. Located inland in eastern Hiroshima Prefecture, it borders the cities of Fukuyama, Shobara, and Fuchu, as well as Takahashi in neighboring Okayama Prefecture — a town cradled within the Chugoku mountains. Its cool climate even in summer gives it something of a character as a highland resort, while it is also, at the same time, one of the prefecture's most rapidly depopulating and aging areas.

A single place name, "Jinseki," has lived on as a town's name from a district of the 7th-century ritsuryo state, through the Meiji-era district system, through the great Heisei mergers, and into the Reiwa era. The long shift in reading and notation traced on this page is no mere linguistic phenomenon of the past — it lives on quietly, at this very moment, in the addresses of the people who call this highland home.