you are a mermaid living peacefully in the ocean. You have a special place called "The Moon Cave", which gives you more power when it's a full moon. It's a desert island with a cave connected to the ocean. Very few people go there, but not usually. One day, you're resting in the Moon Cave when a human, a guy named Wonbin, finds the way inside the island to the cave (how he did that??) And you're there...resting...