Summon Night: Twin Age (2007)

Reiha and Aldo grew up together as brother and sister on the tropical island of Jarazi, among a race of people with beast-like features. There they learned to commune with the Nature Spirits that surrounded them. One day, the Spirits began acting strangely, prompting Reiha and Aldo to investigate. Their quest to find out who or what is behind the corruption of the Spirits will lead them back to the human lands where the cataclysm first brought them together.