Set months after the events of Mobile Suit Gundam Unicorn, the story focuses on two former Principality of Zeon Remnants, Former Weapons Developer Arlette Almage and Former Test Pilot Danton Hyleg. Both of them are hired by the Earth Federation Forces research team to investigate the remains of the asteroid base Axis. But upon their arrival, they encounter a Cyber Newtype, Quentin Fermo, who pilots the mysterious mobile suit, the RX-78AN-01 Gundam AN-01. Tristan attacks them for unknown reasons.