Photo/IllutrationThe point of the “kohoki” blade at Kasuga Taisha shrine in Nara (Kenta Sujino)

  • Photo/Illustraion
  • Photo/Illustraion
  • Photo/Illustraion

NARA--One of the oldest Japanese swords in existence has been recognized as a treasure at a shrine here after being found in an attic decades ago.

When the rusty sword was cleaned and sharpened, it was discovered to be from the 12th century, making it one of Japan's most time-honored weapons, an official of Kasuga Taisha shrine announced Jan. 22.

The discovery means it is a museum piece that will be carefully studied to shed further light on the history of the Japanese sword.

It appears that the “heirloom,” which was made in the Heian Period (794-1185) for a samurai and initially passed down through his family, was presented to the shrine sometime from the Nanboku-cho Period (1336-1392) to the 14th or 15th century, or the early Muromachi Period (1338-1573).

The curved 82.4 centimeter-long sword, without the creator’s name inscribed, is a “kohoki.”

The kohoki sword is one of 12 blades that were housed in the attic repository of Kasuga Taisha shrine and was originally discovered in 1939.

The shrine discovered its real value after whetting the blades from fiscal 2016 to mark its 60th Shikinen Zotai, a traditional ceremony of shrine building restoration held once every 20 years.

Before it was sharpened, the kohoki sword was covered in rust.

Part of the name derives from the Hoki Domain (today's Tottori Prefecture) where a series of kohoki as well as other swords were crafted.

“It is rare that such a long kohoki sword has survived along with parts of its exterior,” said Motoki Sakai, a senior researcher of the history of Japanese craftworks at the Tokyo National Museum.

Certain important characteristics of the kohoki sword including the curved shape that started in the late Heian Period had a major influence on the development of blades from then up to the modern day.

Kohoki and other swords created in the Hoki Domain are believed to be the oldest Japanese swords with a curved shape. Before that, Japanese blades, unearthed at ancient ruins or housed in the Shosoin Repository at Todaiji temple, were straight.

The exterior parts and the scabbard coated with black lacquer were seemingly made sometime from the Nanboku-cho Period to the Muromachi Period.

There is a possibility that a famed swordsmith known as Yasutsuna, whose date of birth and death are unknown, forged the kohoki blade itself as its pattern is similar to that of blades associated with him.

Yasutsuna is believed to have been one of the earliest makers of kohoki swords.

The sword will go on display at the Kasugataisha Museum within the shrine site from Jan. 30 through March 26.

The latest blade will join a cadre of more than 10 kohoki swords that are government-designated national treasures or important cultural properties.