Two young and beautiful girls, Cobalt and Sepia, are speaking about the invasion of Earth in a room aboard a gigantic Cthuwulf spaceship. Cobalt is sent to Earth aboard the Delos Theta, a powerful robot, to stop Iczer-One and prevent her from finding her human partner.
Nagisa, a normal human girl, is going to school when she meets Iczer-One who seems to be waiting for her on the side of the street. She exchanges a few words with her but when she want to show her to a school-friend, Kawai, who has just arrived, Iczer-One seems to have vanished.
At school, Nagisa has an exam but she seems to fall asleep in the middle
of it and "dreams" that she is alone with her friend Kawai when this one
suddenly turns into an horrible monster. Iczer-One seems to be looking over
Nagisa from outside, floating into the air. Suddenly Nagisa "awakes" in the
middle of the test, very confused.
A little while later, she is speaking with friends on the roof of the school when they suddenly all turn into monsters. Nagisa falls from the building but is rescued by Iczer-One who suddenly appears in middle-air. Nagisa flees from Iczer-One screaming and is transported into another dimension where she is attacked by monsters and faint. She is rescued once more by Iczer-One who destroys the monsters.
During that time, Cobalt, aboard Delos Theta, lands in the middle of the city. The army tries to push back the invader with their latest battleship, the Fuji-1, but they don't stand a chance against the power of Delos Theta and are quickly destroyed.
Iczer-One has noticed the landing of Delos Theta and she calls Iczer Robot
to fight it. She brings a still screaming and reluctant Nagisa into the
Robot to fight with her as her partner.
Nagisa still refuses to fight to protect the Earth and Delos Theta seems to be wining against Iczer Robot. Finally Iczer-One persuades Nagisa to fight, if not for her home world, but to avenge the death of her parents. Iczer Robot, piloted by Iczer-One and with the energy of Nagisa, quickly get ride of Delos Theta.