As a boy, he was on at the scene of a disaster as Aftokrator was trying to suppress Galopoula's Mother Trigger. He is approached by Hairein's Expedition Force. Lamvanein asks what they should do with him. Hairein orders Lamvanein to leave him be; he already lost his will to fight.
Reghindetz is part of the force sent to Mikado City on behalf of Aftokrator. While preparing to invade, he constantly questions their actions and the mission itself. During the invasion, he goes out but stays in hiding, and monitors the Trion Warriors' progress. After Koskero is defeated, he decides to join the battle himself. He takes several Dogs and heads towards the city to draw attention towards himself. He has no intention of doing any damage, but, the Border agents do not pay attention to him because, thanks to Jin, they knew that there would be no collateral damage. This frustrates him, but things take a turn when Hyuse shows up. He is unsettled because he was given orders to not accomodate Hyuse, and even kill him if he had to. Then, Yōtarō shows up to give Hyuse back Lampyris. He is also told by Yomi that the mission was a failure as everyone but him was defeated. Seeing an opportunity to pass Border's anger from Galopoula to Aftokrator, he tells Hyuse that he believes that Hyuse is allianced with Border and sold out Galopoula. He tells Hyuse that if he wants to prove himself, he has to take Yōtarō hostage. Rather than merely taking Yōtarō hostage, Hyuse seemingly stabs him. Reghindetz is horrified; killing a child was too far. He informs Hyuse that Galopoula had no intention of returning him, and even planned to kill him if he got in the way. Yōtarō gets up unscathed, and Reghindetz realizes that it was a ruse to find out if Reghindetz was actually going to take Hyuse back. Hyuse points out that Reghindetz was the one who tried to trick him first. Reghindetz is enraged by this; he activates his Trigger. However, he is easily put down by Hyuse and his Lampyris, and he retreats.