Kilian Gaius (or Kai) Engele is the former prince of the Sarian kingdom. Sarians are blue-skinned elf-like beings who have an average lifespan of 100 years. Kai is 16, but had been sealed away within Elementia for 3000 years.

The leader of the group, Kai is serious, cold, and a skilled fighter. He weilds two long-handled swords that can be joined into a double-bladed staff and is also a wind mage. Kai's goal is to stop his brother, Kasukei, from opening the Elementia gate and gaining the power to reshape reality as he sees fit. Kai's outwardly alruistic nature hides an inner darkness... he intends to use Riser as the sacrifice to seal Elementia, so he will not be trapped in the realm again. Kai has a tendency to make snarky comments to those around him.