CNN  — 

Amid the speeches, customary robes and ancient rituals of the enthronement of Japan’s new emperor Naruhito, one might easily overlook the collection of seemingly innocuous items carried in by palace officials.

But among them, hidden in boxes and wrapped in cloth, are two objects so sacred that they’ve never been seen in public – divine artifacts that even the new emperor himself may never have laid eyes on.

The boxes will be placed next to the emperor as he ascends the Chrysanthemum Throne on Tuesday. They are believed to contain a sword and ancient jewel that, according to legend, date back to the mythical forefather of Japan’s first emperor, Jimmu, who ruled almost 2,700 years ago. Along with a fabled octagonal mirror (which plays no part Tuesday’s ceremony), they form Japan’s royal regalia, or the Three Sacred Treasures.

In the absence of a crown, these items serve as the symbolic embodiment of the emperor’s – now largely ceremonial – role. Yet, their condition and appearance remain shrouded in mystery, explained Mickey Adolphson, a professor of Japanese studies at the University of Cambridge.

“The not showing of such treasures is of course an important part of the strategy that adds mystique, and thus, authority, to the objects,” he told CNN via email, adding that the Shinto religious tradition is “especially protective” of its symbols. “Were they for everyone to see, they would not have the same staying power.

“Of course, many historians would like to make a more careful analysis of them… but there is currently very little appetite in Japan for somehow de-mythologizing the objects and I do not expect it to happen in the near future.”

Emperor Naruhito inherits the imperial regalia at a ceremony at the Imperial Palace in Tokyo in May.

Even the items’ usual whereabouts remain a matter of speculation, though it’s believed that the sword and mirror are kept at shrines in Nagoya and Ise, respectively. The jewel is thought to be stored at the palace in Tokyo, where Tuesday’s ceremony is set to take place.

But given that they remain hidden, there’s no real evidence that they will actually be present at the enthronement – or that they even exist, according to adjunct professor of political science at Temple University’s Japan campus, Michael Cucek, who explained that the palace forbids “any analysis of any aspect of the physical manifestations of the Imperial House.”

“We see the boxes, we see that they’re strapped to the staff of the Imperial Household Agency,” he said in a phone interview. “But is there anything in there? No one knows.”

Both the Imperial Household Agency and Japan’s Cabinet Office said they could not provide CNN with comment on the regalia, beyond what has already been published in official histories.

Divine origins

While the earliest historical records of the Three Sacred Treasures date back to the middle ages, the items’ mythology stretches back much further.

Legend states that the Shinto sun goddess Amaterasu bequeathed them to her grandson, Ninigi, as he descended from heaven to bring peace to Japan. The sword, mirror and jewel are said to represent the three characteristics required to rule on Earth: valor, wisdom and benevolence, respectively.

Ninigi is considered a forefather to Japan’s first emperor, Jimmu, whose reign officially dates from 660 B.C. – and from whom a direct line of lineage is drawn to the present-day emperor. The items are said to have been handed from ruler to ruler ever since, and they were formally passed to Naruhito following his father’s abdication in May.

An engraving by Toyohara Chikanobu shows the sun goddess Amaterasu in the right-hand panel with the Three Sacred Treasures.

Over the centuries, the seizure or surrender of the regalia have played a role in disputes and competing claims to the throne. In the 14th century, emperor Go-Daigo is believed to have tricked a rival with replicas as he resisted attempts to overthrow his rule.

It is not the items themselves that legitimize the throne’s rule, however, but the unbroken lineage they represent, according to Cucek.

“The Three Treasures… cannot support the claim of a usurper that he is the true emperor,” he offered as an example. “If you steal them they are worthless. If the imperial line dies out, which is a real possibility (Naruhito has one child, a daughter, though current laws bar women from the throne), they cannot maintain the imperial institution.”

It is, perhaps, fortunate that the regalia do not literally embody the throne’s power – because the originals may not have survived to the present day. Some historians suggest that the mirror was damaged, if not destroyed, in an 11th-century fire, and that little more than fragments remain at the Great Shrine of Ise. Similarly, the jewel and sword were believed to have been lost at sea during a battle in the 12th century, though some accounts claim that they were recovered from the Kanmon Straits (or that, in the case of the sword, the lost item was in fact a replica).

Ongoing fascination

Today, the items are considered more ornamental than divine. This is especially the case since Naruhito’s grandfather, Hirohito, was forced to relinquish the claim that emperors are direct descendants of the goddess Amaterasu in the aftermath of World War II. Yet, little is publicly known about the actual objects’ creation.

Some experts believe they may not even have been produced in Japan, said Cucek, who said it’s likely that they’re all “imports.”

“The mirror is most likely from Han-dynasty China; the sword, whether it’s bronze or iron, would be an import, because there were no metal resources in Japan at the time it was manufactured; and while the jewel is in the shape of a ‘magatama’ (a prehistoric Japanese bead), if you look at Korean items, like the crowns of the kings and queens of Silla (a kingdom that ruled much of the Korean peninsula from 57 B.C. to 935 A.D.) they’re covered in the same-shaped jewel,” he said.

“All three items indicate a connection to continent.”

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Adolphson added that the regalia would have been considered advanced at the time. “The symbolism is most certainly an after-construct,” he explained. “The original value lay in the technology and the rarity of the objects.”

Also on the table at Tuesday’s ceremony will be two royal stamps: the Privy Seal, marked with the characters reading “imperial seal” and “emperor,” and the State Seal, which features the chrysanthemum emblem representing the royal family. Unlike the Three Sacred Treasures, these items served a very practical purpose, having previously been used to officialize laws, treaties and documents.

Yet it is the mysterious royal regalia that have captured the public imagination. Indeed, the phrase “Three Sacred Treasures” has translated into popular culture, having been used in recent decades to describe the coveted technology of the day – the washing machine, refrigerator and television in the post-war era (or 5G, AI and 4K resolution in modern times).

“In a way, it was a democratization of the notion of three treasures,” Adolphson said.