Earth (Buryoku #6)

With the rise of the Ancient Cavern Beast, Furea, the Bringer of Fire, comes a threat the likes of which Buryoku hasn't seen in centuries. As if this wasn't bad enough, his armies rise along with him, containing fighters so powerful that even the Scions may not be victorious against them.

While the war rages on, Roy and Aika find themselves transported to a new land, set on a mission by his mother to hunt down the only man who can truly teach Roy how to control his birthright. Finding him may also unlock the only key to defeating the Ancient Beast.

Roy and Aika race against time even as Sovereigns, aligned against his father, scheme and plot his downfall. The toughest battles Roy has ever faced are on the horizon, and facing stronger enemies than ever before, he must advance quickly or face certain death.