The Kosakas travel to Mahika island in the South Pacific during spring break. Hikaru sends Seiji a video tape of her at the beach. She says that it’s a shame he’s stuck home and that they’re having a lot of fun despite the constant earthquakes. Seiji complains about wanting to go to the island before realizing he actually has the means to do so. He has Jumbo Saber take him and Da-Garn to the island under the pretense of investigating reports of disasters and strange occurrences there. Jumbo Saber and Da-Garn voice their suspicions when they sense nothing out of the ordinary, but Seiji assures them they’re here to investigate. On Mahika island, the Kosaka’s visit a zoo and Haruo briefly complains about humanity locking animals in cages and building resorts on uninhabited islands before being distracted by a lion. Seiji leaves his Director with Da-Garn and runs down to the beach after agreeing to Jumbo Saber’s suggestion to call the other Sabers to help with the investigation. Jet Saber and Shuttle Saber are also suspicious of Seiji’s intentions, but Da-Garn assures them that Seiji is the chosen one and cannot make mistakes. At the bottom of the ocean nearby, Redlone’s robot soldiers are using another drilling machine to tap into a planet energy reservoir and Redlone’s rebuilt assistant informs Redlone that they will make contact with the reservoir soon. Activating the reservoir will cause violent seismic activity on the Earth’s surface and produce plenty of planet energy. However, upon making contact no planet energy reaction is detected and Redlone angrily splashes his wine on his assistants face. Just then they detect the Sabers flying overhead and Redlone gets the idea to use the drilling machine to cause a nearby underwater volcano to erupt. The Sabers spot the eruption and are immediately attacked by combat trooper Selene Alpha. They tell Da-Garn to find Seiji because they can’t fight back without his order. Da-Garn quickly rushes to the beach but fails to spot Seiji playing underwater with some girls. The volcanic activity causes a tsunami that Selene Alpha uses to power his energy beams and blast the Sabers. Redlone’s assistant comments that if Selene Alpha receives enough pressurized water its engine will overheat and cause a massive explosion, taking out the Brave Fighters with it. Hikaru briefly spots Seiji playing with two girls but doesn’t have time to confirm that it’s him before everyone at the beach notices the incoming tsunami. She runs to her parents to escape to high ground.
Da-Garn locates Seiji and tells him that they must evacuate quickly before the tsunami hits. Seiji thinks the tsunami is too far away but is shocked when Da-Garn informs him that it was caused by Redlone’s combat trooper who is now attacking the Sabers. Seiji quickly orders the Sabers to return to the island but Selene Alpha grabs Jet Saber with its tentacles. Seiji sends Da-Garn to assist the Sabers and has him combine into Da-Garn X. Jumbo Saber and Shuttle Saber attack Selene Alpha with Jumbo Tornado and Shuttle Flasher to free Jet Saber but the attacks have no effect. Da-Garn X arrives and kicks Selene Alpha, allowing the Sabers to free Jet Saber. Selene Alpha fires missiles at Da-Garn X but the latter destroys them. Da-Garn X tells the Sabers to return to the island while he handles the combat trooper. Redlone orders Selene Alpha to focus on Da-Garn X and his assistant warns that they need to evacuate the area. Redlone orders the ship to surface just as lava erupts from the ocean floor. The lava destroys the drilling machine along with the soldiers working on it and Redlone orders his assistant to save the video feed for his collection. Seiji suits up and lands the Sabers near the panicking tourists. He tells everyone to board Jumbo Saber and they quickly comply. Da-Garn X knocks Selene Alpha around but the latter flings him away. Da-Garn X blasts Selene Alpha but his attacks have no effect and the latter electrocutes him with its tentacles. Seiji spots Hikaru and lowers his helmet visor before she can see him. Hikaru says that the zoo animals haven’t been evacuated and Seiji orders the Sabers to take off while he rescues the animals. Using a pocket laser, he destroys the locks on all the cages. The Sabers deposit the tourists safely on a plateau and rush back to help Da-Garn X, who Selene Alpha has bound in the path of the tsunami. The Sabers fire simultaneously at Selene Alpha but their attacks have no effect. Seiji herds the zoo animals towards higher ground and asks the Sabers if there’s any way for them to become stronger. The Sabers reveal that they can combine and Seiji wastes no time ordering them to do it. The Sabers immediately combine into the giant robot Sky Saber! Sky Saber uses his Sky Boomerang to cut Selene Alpha’s tentacles just before the tsunami hits, allowing Da-Garn X to escape the combat trooper’s destruction. Seiji’s joy is cut short when he realizes he still hasn’t climbed high enough to escape the tsunami. Redlone appears and fires upon the Brave Fighters while cursing them for foiling his plans. Da-Garn X tells Sky Saber to rescue Seiji while he handles Redlone’s ship. The tsunami demolishes the beach resort and Sky Saber barely manages to grab Seiji before he is completely swept away. Da-Garn X uses his Da-Garn Blade to slice off one of the ship’s wings. Against his assistant’s protests, Redlone retaliates with missiles but Da-Garn X destroys all of them before wrecking the ship. On the way back, Seiji falls asleep from exhaustion and Da-Garn X tells the Sabers to run their engines low to avoid waking him until they reach Japan.
At this point, I’m starting to get convinced that the show isn’t interested in pointing out that Seiji occasionally slacks off in his duties so much as that he has a knack for finding trouble wherever he goes. Not that there was anything wrong with Seiji indulging in the perks of having a private jumbo jet at his beck and call now that he found all the Brave Stones and has no immediate matters to tend to. On the other hand, Redlone hasn’t had as much luck finding planet energy reservoirs as Seiji did finding the Brave Stones. Although we now know that his definition of beauty includes scenes of things exploding, which makes me wonder what he’d think of Michael Bay movies. Haruo indulges in a bit of obligatory environmentalism, but it’s hard to take him seriously when he’s doing it from the comfort of a tropical island.