Hajime, a young man who has returned to his hometown from Tokyo, heads out to explore a cave with his childhood friend Umi and five others on a local mountain, Mt. Shirao, which is famous for its legends. However, it turns out to be a different world where something spectacular and unprecedented awaits them…!? Is it a monster or a god protecting this area? The despair the group witnesses as they advance through the lightless hole is…! A new release from the animal horror master Okada Takuya, a shocking caveman panic grandly appears!