The film opens with Fuyuki Hinata and the Keroro Platoon exploring an abandoned temple atop the mountaintop city of Machu Picchu in Peru. During the exploration, Keroro accidentally triggers a trap, leading them to a hidden chamber that houses a large blue crystal on a stand, accompanied by a key. When Keroro leans against the key, the chamber activates a mysterious machine, causing the entire temple to shake. Realizing the danger, the group rushes out of the room. While running, Keroro loses his Kero Ball, and Fuyuki catches a fleeting glimpse of a glowing young woman as they exit. Fuyuki tells Keroro that there was a girl in the room, but he is forced to leave.