C1720 The battle of the lower city of the sacred grounds preface!

BOOM!

A huge sound wave roared over like a tsunami. The earth's crust above Saint Underground City was penetrated, and the ground above Hope Square collapsed all of a sudden, as sunlight and giant rocks fell down together.

The earth's crust above the Saint Underground City was a few kilometers thick, but it was actually penetrated by the ground gunboat!

Destroying a land