The Day the Stronghold Fell. The Black Relic and the Medusa return to Earth assisted by Zell, but Muetta is consequently arrested. Zell states that Yukihime died 450 years ago and Muetta is a replica based on her genetic information. He further explains that Efi Dorg creates clones of the lifeforms that they conquer and embeds false memories in them to be loyal vanguards. He also tells Yukina that her father Takehito was a close friend. While citizens are evacuating, the Efi Dorg Spaceship launches multiple geoframes, including the Rockhead, the Bluebird and the Spider. Zell attaches the Crow to the Black Relic so Kennosuke and Yukina can confront Yoruba. Tom, Shenmei and Sebastian engage Imusa, Mirasa and the Headlesses on the ground using single-seater GAUS units. As the battle grows fierce and the research facility soon breached by the Headlesses, the Efi Dorg Spaceship drops many Cactuses, which release electronic parasites that take control of some of the staff. Sophie gets her friends to rescue Muetta from an overturned van, while Sebastian sacrifices himself in an attempt to destroy the Spider. Kennosuke and Yukina in the Black Relic pick up Tom in his GAUS 1, and they depart from the overrun research facility.