Kai is a bio - mechanical android like cell and other androids. He's an new creator and replace Dr.Gero because of his death and meets him as an hologram / talking computer. He's been created by Dr.Gero as a secret weapon in an underground laboratory before their death. Kai recreates Dr. Gero's pototype androids into something stronger and better. His androids are 2 , 3 , Android 27 , Android 28 , Android 29 and Android 30 being activated to find Goku but they don't know he already died and they fight Trunks and the new Z Fighters instead.
Kai is in his underground Lab in an different location along with his androids and he had an assistant named Jiro.