In the year 2062, Earth finds itself engaged in a ferocious conflict with Artemis, an AI that turned against humans when a massive labor automation project failed years earlier. The guardians of mankind, a trio of exceptionally competent human fighters, have gathered in the hopes of winning the battle. The final guardian, Empress, awakens by herself at a deserted research facility. She starts looking for answers since she can only remember the name of a place named "Lighthouse No. 8" from the past. She quickly learns that Artemis is about to pose a threat, and that she is the only one who can prevent the end of the world.