Sairaorg first used this form to outclass Issei using Welsh Dragonic Rook, blocking his strongest move using a single hand, then penetrated his armor using a single punch, knocking him unconscious. Regulus Rey Leather Rex is Regulus Nemea's Sub-Species Balance Breaker, which covers Sairaorg in a golden lion armor similar to Scale Mail, increasing his offense, defense, and speed to a drastic extent, focusing its power into his fists.

He was easily able to defeat him, destroying his Holes, which previously repealed all the attacks that Sairaorg and Saji used against Bedeze. Sairaorg used his Breakdown the Beast in Volume 21, during his battle against the current 3rd Ranker of the Rating Games, Bedeze Abaddon. Sairaorg later fought Issei, who had unlocked his Crimson Armor, with Sairaorg losing as he was knocked unconscious while still standing up. However, due to being moved by Issei's determination to fight him with everything he had, Sairaorg combined with Regulus into this form, as he overwhelmed Issei's Triana Rook form and incapacitated Issei with a punch, rendering his unconscious.

In Volume 10, during his fight with Issei, Regulus asked Sairaorg to combine with him, stating that with their Balance Breaker, Sairaorg would easily win against Issei, though Sairaorg refused as he swore to only use it in the defense of the Underworld. 3.1 Regulus Rey Leather Rex Imperial Purpure.

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