Before the last battle of the angels and demons, Ethriel Morrow-the head of the demon troops assigned to steal an orb called "Heaven's Heart" that heaven will use to defeat Satan. During the armageddon, Arcangel Gabriel travelled in the land of mortals to hide the orb away from the demons. Ethriel follow Gabriel to the land of mortals to fight and to steal the orb but he failed. Arcangel Gabriel casts a spell to hide the orb in the heart of a maiden. When Ethriel go back to hell and report the failed mission to Satan, Satan punish him together with Alciel and sent them in the land of mortals to find the orb but not as demons but a mortals.
A man is whisked off into a spaceship where he meets a woman. She wants to get to know our species. After the man spends some time with her, she accompanies him in the form of a technology, helping him out of tough situations while sparking the interest of some governments.