Casey Stone is accused of summoning the destructive Nightmare Beast and branded the Beast Realm's Scourge, facing sacrifice to appease the heavens. She insists her sister Melly framed her by transferring the Nightmare Beast onto her. Casey tries to summon her Beast Horde to prove her innocence but fails due to low spiritual power. Lucian reveals the person she has been bonding with is not him, but a lowly Rat-man, exposing a betrayal that blocked her power advancement. Melly claims Casey's taming art as her own. Despite this, Casey survives, vows revenge, and prepares to confront Melly and Lucian’s treachery.