This cave is said to be the location of the legendary Shizunoiwaya monument, which was written of by Oishi-no-Suguri-no-Mahito in the ancient Manyoshu anthology. The cave has two mouths and is 45 meters deep and 13 meters high. The bedrock was formed by the deposition of volcanic ejecta about 15 million years ago, and the faults and dikes are intricately intermeshed, revealing the intensity of the crustal movements that formed the Japanese archipelago.