Dr. Mikoto is a Hunter-Human, DinoHunter and scientest who joined the Death Corpse. He lives on Huntaworld has a enemy of Dino-Earth and Evolien. According to Top Galer, he's smarter than Samuel does built the MegaZORD or something else like before.
After Shadow's death, he's first appeared as a shadowy person who claim this world much as Eustace's shocked. Dr. Mikoto now fully appearance and has a Shadow's Samuel cell to create a ultimate MegaZORD (before a special episode). Mikoto creating the stronger Takugamis and Gigamis.