Kai is the Ninja of fire.Kai is also brother of Nya.Before he meets Sensei Wu, Kai was determined to be a better black smith than his dad.In the first episode he messes up on the sword he was making.He is also the carrier over the sword of fire. Also in the first episode Kai disobeyed Sensei Wu and used the scythe of quakes.Also when him and Nya were children their dad told them stories about the dragons, and how the live in both worlds.

Having proven himself as an equal member of the team, Kai is ready to take on new challenges. He has a strong sense of justice and will fight anything, bend any rule and burn any bridge on his path.