Izu, Shizuoka The Nirayama Reverberatory Furnace (韮山反射炉, Nirayama Hansharo) is a well preserved iron smelting facility. Built by the Tokugawa government in 1857, the furnace represents the start of modern iron production in Japan. Originally part of a larger factory complex, the furnace was constructed of local stones and bricks. It represented the most advanced technology of the time, and iron produced there was processed on site and cast into cannons, which were desperatel