Yomi is an agent from Galopoula under Gatlin, sent to cause mayhem such that Border could not send retaliation and recovery forces against Aftokrator. He first appears when he scouts the area of a recent fight between Katori Unit and a few Trion soldiers. During the blitz, he monitors Koskero, Reghindetz and the Dogs. He the joins the fray by controlling two Idras in Manual Mode, flanking the Gunners. He is intercepted by Hisato, whom he manages to wound, and Futaba. He engages Hisato and Shinnosuke with one of the two Idras, Futaba and Ai with the other. Although the two defeat it almost immediately with a combination of Spider and Idaten, he immediately takes control of another Idra. Thanks to Tsukihiko's Side Effect, he is instantly located and targeted by Ai and Futaba. However, having understood the mechanics of Idaten, Yomi manages to counter Futaba's attack, wounding her in the process.
Following Gatlin and Ratarikov's defeat, he orders the Trion Warriors to retreat. Back on the ship, he analyzes Vasilissa's broken arm, concluding the fracture was due to the overlapping of two attacks.