Sayonara Lara

Long, long ago, there lived a mermaid princess named Lara. She was raised with love by her father, the king of the sea kingdom, and her older sisters.

One day, Lara fell in love with a human prince who lived on land. It was a forbidden love, one that was not allowed in the world of mermaids. Still, Lara journeyed to the surface. 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, she would turn into foam. Though she was a princess of the sea, Lara chose love. Yet, her wish went unfulfilled and perished into the sea.

Two hundred years later, Lara awakens once more in Lake Biwa to finally search for her true love.

All because of "love".

(Source: Crunchyroll News, edited)