Underwater Battle! Giga Shooter is Ready!. Build base to grasp the current situation in the zone and to quickly restore the equipment. Kenji, who has no choice but to watch, goes out to reconnaissance on a thunder horse. On the other hand, Commander Tamaki and Senjiro Shiba carry out an investigation of the old build base that was in the zone in order to collect data. Commander Tamaki and Senjiro visit the old build base and find out that the inside of the zone hasn't changed at all from 50 years ago...