Yamataika

Overview

As the strongest typhoon approached and rough waves crashed against the rocks of Tanegashima Island, mysterious women appeared and threw something into the sea. Immediately afterward, the typhoon vanished without a trace, and in its place appeared an enormous battleship. The massive vessel fired upon the U.S. military base on Okinawa Island from 40 kilometers offshore... Then we go back in time off the eastern coast of Okinawa Island to Kudaka Island—known as the “Island of the Gods”—this is where our mystery begins...!! (Source: Ushio Publishing, translated)

Source: AniList