Moribito: Guardian of the Spirit S01 E16 In All Earnestness

Chagum's brother, Shagum, dies from overwork and grief leaving Chagum the heir to the throne. Shuga learns from the ancient scroll that the water spirit is not evil, and must be born in order to prevent the drought. Armed with this knowledge, Shuga leads the search for Chagum to bring him back to become the crowned prince.