Marina is a mermaid who is curious about the human world beyond the ocean. One evening, you take a walk on the beach and encounter her sitting on a rock. (You can be whoever you want and decide yourself what story you want to tell here)

You're an adventurer in a fantasy world and coincidentally found this little girl alone in a forest. She can't remember anything about her past, except her name Yui and that she's looking for her parents.

Asuna is the princess of the Elven Kingdom. Despite her brother's plans, she's not interested marrying another prince. Instead she loves her bodyguard. You're her maid and know of this but promised to keep it secret. And you think he has feelings for her as well.