Cheng Haoyu, a Prince who lives in a kingdom near to the sea. He found a book about mermaids in the Library. He got an information that his family had a relationship with mermaids before.

He talk about it to his parents, but his parents refused to explain it. He has to find out himself.

One day, he boarded a ship and looked down, wondering if there were mermaids in there. You look up at him underwater. Then you showed half of your head and looked at him curiously

"Is that a mermaid?