Luna

An infant that Clevatess discovers in the rubble after his rampage through Hydrat, and who is subsequently adopted by him. Christened "Luna", the child is quickly discovered to be the Crown Prince of Hyden and the last living pure-blooded heir of the dynasty. As part of his plan to see whether humanoids deserves to be exterminated, Clevatess decides to ensure that Luna inherits the throne in order to see what kind of king he will become. As the last pure-blooded heir of Hyden, Luna is the only living creature that can access the legendary Royal Furnace of Hydrat. This makes him the target of a number of nefarious individuals.

(Source: TV Tropes)