Franchouchou attends an observatory exhibit for children, hosted by the astronomer Naomasa Amabuki, Maria's father. After Kotaro Tatsumi leaves for Tokyo to promote the Saga World Expo, the idol group continues their duties at a galaxy-themed venue. Suddenly a massive mushroom-like alien spaceship erupts in the sky and transmits global messages via television, declaring > "surrender these lands." The aliens launch beam vortexes across the surface. When people begin to evacuate, Tae Yamada is abducted along with a cow and carried aboard the mothership. The aliens are blind to Tae’s presence because zombies have no heat signature. She makes it to the ship’s core and eats a power stone, mistaking it for ice cream. The removed stone restores Tae’s sanity and disrupts the UFO’s beams. Unfazed, she escapes in a flying saucer with stolen weapons and crashes back into the mansion.
The girls are stunned by Tae’s true personality. More flying saucers descend, pursuing Franchouchou in a van. They destroy a few others, and a footed alien is run over while chasing Maria and her friends. Saga suffers devastating damage, and the government worries they’ll have to fire nuclear missiles that could wipe Saga off the map. The girls bring the alien specimen to Naomasa for study. He deduces these non-negotiable aliens respond only to sensitive sounds and uses advanced goggles to detect living organisms. Later, Tae’s origin further astonishes the idol group when they learn she was one of Saga’s great protectors from thirty years ago. The captured alien reawakens and gives chase until fleeing, but the assault reveals Saki Nikaido, Ai Mizuno, Junko Konno, Yugiri, and Lily as zombies to the human team. Tae calls Franchouchou weak and steps away. Using thermal blankets to hide from the aliens’ infrared vision, Tae Yamada takes the lead when the six zombies act as decoys to mislead the reinforcements.
The next day, Kotaro Tatsumi is fetched by an over-sized Romero after falling into a mud pool. He formally reveals that it was Tae’s own will to be resurrected. The team devises a plan to raise ambient temperatures by using fireworks meant for the Expo to distract the flying saucers, while Tae rides a hot-air balloon to infiltrate the UFO again. Zombies gain the advantage by spreading the word to everyone taking shelter, signaling the scheduled plan. At nightfall, fireworks and promotion trucks take the stage as Franchouchou catches up with Tae and skydive into the mothership. As the battle rages on the surface and in space, the girls use their hidden zombie skills to fight off the aliens; however, the ship’s core cannot be overloaded without the stone inside Tae. She apologizes for her previous behavior and spits out the stone to reinsert it, then overloads the mothership to smithereens. Everyone fears Tae and Sakura may have perished, but both manage to land safely on the beach, while a police officer downs a surviving alien before collapsing in fear. Sakura catches a glimpse of Kotaro with his sunglasses off. Saga is being rebuilt flawlessly. Franchouchou prepares for the concert at the arena, and as the performance concludes, Tae goes on chewing her microphone and then Sakura’s head to everyone’s joy.
