Born through mutations, E's possess abilities that far exceed normal human beings.
15 year old Kai Kudo -who has powers different from the rest of the E's- together with his sickly sister Hikaru was protected from a world that fears E's by an organization called ASHURUM. ASHURUM is one of the 12 corporations that now rules the world. Scouted by Eiji, Kai was delegated to the ASHURUM special force AESES and undergo intensive training, such as sharpshooting, martial arts, and hacking, not to mention psychic training.
Whenever he was free, Kai visited Hikaru at the hospital belongs to the organization, but Hikaru's condition never improved. After one year of training, Shen-lon-another psychic in AESES who felt threatned by Kai from the first time he saw him- told Kai Eiji really only wanted his sister Hikaru, because she was said to have had amazing psychic powers, but was too sick to use them. Shen-lon told Kai that Eiji was just hoping Kai would have those amazing genes too, and was using him.
Not believing, Kai went on a big mission with the other E's to Gald city to infiltrate a hideout of guerrillas that was said to have been using psychics against their will. While on the mission however, Kai encountered civilians that were said to have been evacuated. While trying to save them from the melee, one-afraid of the E's-shot and killed his partner. Kai, distraught, felt a strong telepathic surge attack another of his friend's minds. Still shocked from all that had happened, Kai tried to help the girl, but met up with his rival, Shen-lon, who had a hate for the humans who he believed had hurt his sister. In a rage, Shen-lon unleashed a psychic blast that decimated half the city. Later washing up on shore, Kai was found by a girl named Asuka. After nursing him to health, Kai later found out from her friend, Yuki- a "handyman" that did odd jobs, or whatever was required for money-that he would not be able to get his psychic levels back to what they were unless he went back to ASHURUM. After seeing more of the city and spending time around the people he fought to protect, Kai decides to stay with Asuka and Yuki a little longer...