Arafune Fuketsu is one of the national historic sites located westend of Gunma Prefecture. It was used to for the storage for silkworms. Silk was very important products in Meiji Period. It was one of the biggest exporting products that help Japanese industrial revolution. It is the largest wind cave for silkworm and because of its historical value, it is registered as UNESCO World Heritage Site.
The altitude of the cave is 840m from the sea level. Therefore, cold wind brows from the cave even in Summer.