Tikai is a character that first appears in Sonic Adventure. She sealed herself inside the Chaos Emerald along with Perfect Chaos to stop him fro flooding the world. On Eggman broke the emerald's seal to release Chaos, Tikai was also released. Tikai tried to search out and find a hero who could face Chaos and found someone in Sonic the Hedgehog and his friends.
Throughout most of Sonic Adventure she does not show her true form only appearing as balls of light that provide the player with hints. At certain points Tikai seemingly takes the player back in time to her home village to witness the events that led to her and Chaos being sealed in the first place. Once Chaos absorbs the final emerald Tikal reveals her true form to Sonic and his friends.