Hyrein/Plot

Background
He descends from House Beltiston, one of Aftokrator's four major families. As the head of the family, he increased their power by collecting Trigger users. With the issue of the dying god, he planned to raid Earth to find a suitable candidate. He researched Earth well before the Rad Infestation. However, if he were unable to find a suitable candidate, he would propose Hyuse's family head as god. Out of political alliance between his and Mira's family, either he or Ranbanein is slated to marry her.

Large-Scale Invasion Arc
He is the captain of the force from Aftokrator sent to Earth. He mainly gives orders to his teammates and has Mira find information on Border agents. Later, after Chika and Osamu destroy a Rabbit, he decides that things were going badly and enters the battlefield himself. He uses his black trigger, Alektor to cubify Chika, and pursue Osamu, who is carrying Chika's cube. He is blocked by Izumi and Karasuma, both of whom he manages to take down without considerable effort. With all barriers out of the way, he now follows Osamu, and manages to cripple him. When he is about to attempt to take Chika, Miwa fights him, proving to be a much more difficult opponent due to his Trigger's resistance to Alektor. Mira warps Miwa away, and he then attempts to use Alektor on Osamu, who is now trapped by Mira meters away from the entrance to HQ. Osamu reverts to his living body, rendering Alektor useless. He attempts to physically take away the cube from Osamu, but is attacked by Miwa once again, who uses Replica's information and Fūjin to strike him. He manages to get the cube in Osamu's hand, only to realize that it was not that of Chika's, but one that he himself made by cubifying Osamu's Asteroid. However, he cannot look for Chika since Replica has forced the ship to retreat. So he and Mira flee with Viza, leaving Enedora (who has been killed by Mira) and Hyuse, according to plan. Later, in the ship, he points out that while they were unable to capture the golden chick, they completed their original objectives concerning Enedora and Hyuse.

B-Rank Wars Arc
Enedora reveals that Hyrein is the head of one of the four major families in Aftokrator. He explains that if he could not retrieve a candidate for "god" from Earth, he was going to propose the head of House Ellin. This is why he decided to abandon Hyuse. Enedora believes that he used omission to achieve this; he privately told Enedora that the secret mission was to abandon Hyuse, while he privately told Hyuse that the secret mission was to kill Enedora.

Later, during the Galopoula Invasion, as Yōsuke has a brief flashback of Hyrein when comparing him to Koskero in that they were both enemies he had to fight without touching.