Cow's Paradise is a dungeon only found in Atelier Ayesha: The Alchemist of Dusk. This is one of two special dungeons that can only be unlocked through downloadable content, the second being Hidden Paradise. Though this dungeon is formally unlocked right after you rescue Nio, you must significantly upgrade your equipment before heading there. The enemies there are quite difficult, and bringing along a big stack of powerful healing and attack items such as the Forbidden Capsule and Mirage Mirror is highly recommended.