Chiteikai Kidan

Bijou village is rumored to be visited by monsters from the mountains. Hachi and Ichinoshin, who live in the village, have been trying to protect the village as a vigilante group, but one day, the monsters come down to the human village. In order to protect their village, Hachi and Ichinoshin head for the Mijo Mine, the source of the creature. What they find there is a vast underground city.