Collect ALL five Tori birds hidden in the game to Unlock Sky Roost. The Tori birds are hidden in each of the Worlds (besides World 4 and 6) in one level. Search for a 'cloud ground' section during a level and when you reach the end of it you will come across an egg which you must hit to obtain the bird. The Tori birds are located in the following songs when you press the Y Button: The 4th level of World 1, the 6th level of World 2, the 7th level of World 3, the 8th level of World 5 (unlocked after beating the game), and the 3rd level of world 7. When you have obtained ALL the Tori birds return to Symphony City and go to the locked door near the city where you will be able to unlock it and enter into the hidden final world.