Goodbye, Lara

With a potion, given to her from the witch Grace, she became human. But the potion came at a cost—fail to find true love, and she would turn into foam and vanish into the ocean. Though she was a princess of the sea, Lara chose love. Yet, her wish went unfulfilled and she vanished into the sea. Two hundred years later, Lara awakens once more, in Lake Biwa to finally search for her true love.

(Source: Crunchyroll)