吉見百穴

Yoshimi Hyakuana - Yoshimi Hyakketsu - Yoshimi Hundred Caves


Useful Information

Location: Near Yoshimi. Kanetsu Expressway, Higashimatsuyama exit, towards Konosu.
Open: All year daily 8:30-17.
[2020]
Fee: Adults JPY 300, Children (6-10) JPY 200, Children (0-5) free.
[2020]
Classification: SubterraneaCave Tomb SubterraneaFactory
Light: electric
Dimension:
Guided tours:
Photography:
Accessibility:
Bibliography:
Address: Yoshimi Hyakuana, 324 Kitayoshimi, Yoshimi, Hiki District, Saitama 355-0155, Tel: +81-493-54-4541.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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History

1887 first excavated by Tsuboi Shōgorō, a professor at Tokyo Imperial University.
1919-20 underground factory constructed.
1920s further research by Mitsutarō Shirai and other archaeologists.
07-MAR-1923 designated a National Historic Site.
declared a National Natural Monument.

Description

吉見百穴 (Yoshimi Hyakuana) or The Hundred Caves of Yoshimi is one of the most impressive archaeologic sites of Japan. The hillside of volcanic tufa was used to dug 219 cave tombs more than 1,400 years ago in the Kofun period. It is the largest cluster of cave tombs in Japan.

The tombs have an entrance which is about one meter square, the size varying slightly due to the topography. Behind the entrance is an entrance tunnel of the same size leading to a larger burial chamber. The chambers are severl meters long and many have an elevated structure, which may have held coffins or the bodies. Some chambers have multiple pedestals, which suggests that they were used for multiple burials. Today all the entrances are open, but it seems they were once sealed by schist slabs.

The caves were first excavated by Prof. Tsuboi Shōgorō from Tokyo Imperial University. He was one of the pioneers of Japanese archaeology and anthropology. He dated the caves to the Jōmon period because he discovered pottery fragments from this period at the site. His theory that the caves were originally dwellings for a race of people smaller than the modern Japanese was later challenged. It seems he used a little too much fantasy and old legends of dwarfs instead of common sense.

Almost as fantastic as dwarfs is the light emitting moss which was discovered in the tombs. Named Hikarigoke (Schistostega pennata), it requires constant temperature and humidity. It is normally found only in the mountains to the north, this is the only occurrence in the Kanto plain. The caves were declared a National Natural Monument because of this moss.

But actually this are three subterranean sights packed in one. The second one is an underground munitions factory which was built 1919-20 in the nearby hills. And the thirs is one level deeper, below the tombs. During World War II the Japanese Military used this site to construct an underground aircraft engine factory for Nakajima Aircraft Company. Two U.S. air raids in November and December 1947 had devastated the production capacity of Japanese aircraft manufacturing plants. They used this place simply because the soft, suitable rock is only found at this spot. The war ended before the factory was completed, but several tombs were already destroyed.

The site has a small museum, it is possible to visit a few of the tombs and the underground factory.