The Realm of Darkness (闇の世界 Yami no Sekai?) is a realm made up of the Darkness in people of every world. As with the Realm of Light, this realm has a Keyblade, the Kingdom Key D, which King Mickey managed to obtain. Kingdom Hearts is found here within its deepest depths, though it can only be accessed when the Final Keyhole is unsealed. This is also the home of all the Heartless and where the most powerful ones can be found. The Realm of Darkness appears as a playable world known as Dark World in Kingdom Hearts 0.2 Birth by Sleep -A fragmentary passage- with Aqua as the main protagonist.