Iwashita cave is located in the sandstone outcrop which is 200m high above sea level, on the southern slope of Mt. Ishimori. It was originally discovered by J.H. students brimming with full of curiosity in 1964 and official excavation started. Lots of ancient relics of Jomon-era (about 8,000 years ago) were excavated. Most of them were hunting tools like stone arrowhead and that remains are thought to be as one of the base of hunting and gathering society. 29 buried human bones were unearthed from the cave and it showed how they were buried after death at that time. It also tells us that the place for daily life and burying place were separated.