Elebits: The Adventures of Kai and Zero Unlockable: The Night Omega
You must collect all seven pieces of the diary to unlock the Night Omega. Here are their locations::
World 1 (Elebit Forest) - In the right corner of the map is a hidden area. In the bottom left corner of this hidden area is a crack. Inside is someone with the first piece of the diary. Elebits needed: Surf Omega, Ice / X Ice / Blizzard Omega, and Earth / X Earth / Land Omega.
World 2 (Elebit Mine) - There is a hidden area deep within the mine, in the upper left corner of the map. You'll find a hidden crack here. Don't get on the trail cart here. Follow the tracks and you'll see someone with the second piece of the diary. Elebits needed: Flying Omega and Earth / X Earth / Land Omega.
World 3 (Resort Island) - One of the village people has the third piece of the diary.
World 4 (Ice World) - You'll need the X Wind Omega for this one. Use it to turn the spinning wheels with arrows pointing to a certain direction. Follow this to a resident in the middle of the area with the fourth piece of the diary. Elebits needed: X Wind Omega.
World 5 (Ruined World) - After subduing the second volcano, there is a small hut in the upper right area of the map. You'll find the fifth piece of the diary here.
World 6 (Sea Temple) - The sixth diary can be found in the east side of the maiden's shrine, in the bottom left corner of the map. Elebits needed: Fly Omega, Radar Omega, and Earth / X Earth / Land Omega.
World 7 (Libra Of Crystal) - After collecting the previous six pieces of the diary, the sealed golden door at the first floor of the upper left corner of the map will be unlocked. The final piece is inside!