Mizusaka Koi, serving as Geyzamermaid to assist patients with rehabilitation, is suddenly attacked by the Invader aliens. Sensing danger, she secretly transforms while evading the patients' eyes and barely saves her life. Yet even after overcoming this crisis, a new threat emerges—Destroyer Beast Klarugen, a powerful entity too strong for her to defeat alone. To warn her comrades of the danger, Geyzamermaid decides to evacuate the patients, but Klarugen unleashes relentless special attacks with jellyfish tentacles and sea serpent bites. Additional enemy soldiers arrive, worsening the situation. Then comes the shocking revelation: one of the patients who returned to her is actually Invader commander Gadia. He seeks the location of the giant robot "Jujuushin" possessed by Great Geyser, intending to destroy it. Only one hostage is needed to extract the information—precisely why the weakest member, Geyzamermaid, was targeted. How will she stand against overwhelming odds to protect Jujuushin, her allies, and Earth itself?! [BAD END]