Lake Emirisu (エミリス湖) is a location in the Eastern Continent. It is the site of a sunken castle that is now a minor tourist attraction. The location is incomplete and as such has little in the way to offer.
In the first map is a price-gouging harpy who will sell you sponge cakes for a random amount of gold, usually in the thousands. There is also a time witch here seated behind a crate.
The second map to the north is the castle site itself. The only point of interest is the pharmacist in the northwestern section on top of the castle who sells powerful potions and ether together with a Maiden's Kiss item. At night the place will be empty save for a female mage to the southeast who will randomly toss stones at you if you are nearby.