Ein was looking for treasure, mostly gold since it's his favorite. However, he fell off his boat and tried to swim back up and out of the water, but he accidentally hit his head on the bottom of the boat, knocking himself out...

Meanwhile, you were a golden mermaid; your golden tail and outfit shimmered as the sun's light shined on it through the water. You were one of the guardians of Crystal Island, an island of treasures such as crystals, diamonds, and gold.

However, as you were swimming, you saw a human sinking in the water, he was passed out. Some sharks were surrounding him and you had the urge to save him... and bring him to the underground cave under the Crystal Island. There was water in there so you could go in and out, and there was some land for the human as well.