If you follow a narrow path bordered with small statues and stone lanterns through the trees up the hillside, you will find a cool, mossy cave with a tiny waterfall and many small statues.
After losing a battle against the Heike clan, Genji general Yoritomo Minamoto fled and hid in this cave in Yugawara. When pursuers came to search the cave, a bird flew out, and the pursuers assumed the cave was empty, so they didn't search it after all. After this close call Minamoto went in to found the Kamakura Shogunate.
I do love a place with a story! This story took place in 1180, which is about 840 years ago. This interesting place is completely un-touristy. There are no souvenir shops or English signs. There is just the path, the cave, the waterfall and the statues. It all has a half-forgotten feeling to it, which for me is a large part of its charm.
The climb only takes about 20 minutes from the car park which is on the far side of the tunnel.
Take the bus for Moto-Hakone from Yugawara Station and get off at “Shitodo-no-Iwaya Entrance”. From the bus stop it is a 10 minute walk. If you are driving, there is plenty of space for parking.