During an archaeological expedition in Iraq, a team stumbles upon ancient artifacts foretelling the arrival of a powerful new civilization heralding the downfall of humanity. Simultaneously, in Graviton City, the escalating feud between A-Ko and B-Ko over Kei reaches new heights as Mr. Daitokuji orchestrates a marriage between Kei and Miss Ayumi. Incensed by the proposal, both A-Ko and B-Ko join forces to thwart the impending wedding, unaware of a looming threat as another extraterrestrial armada heads towards Earth.