Cloud Bomb, Earth-Penetrating Missile

"These Stone Ninjas sure know how to dig!" When Yueguang Han reached the border between the Land of Earth and the Land of Hot Water and used his sonic radar to detect the situation along the Land of Earth's defense line, he couldn't help praising them aloud. Just how insecure were these Stone Ninjas? If this had been him a year and a half ago, he probably wouldn't have had any way to deal with such a defense line either. Even large-caliber naval guns couldn't completely destroy it.