It is said to be the best among Eastern World. 3,500m in total length. A vast stalactite cave. Natural treasure of the prefecture designation. 600m of those is open for the public. Stalactite and a stalagmite shine beautifully. It is like the jewel studded with. Rocket rock, Christmas tree, Niagara Falls. The name is acquired to a form. It is a work of art which nature creates.