Title: The Mermaid , Mermaid Princess , Ingyeogongju , InGyeGgongJu , The Idle Mermaid , La sirena , Princesa en exceso , Ingyeogongjoo, 잉여공주

Ha Ni is a mermaid princess in the underwater empire, but she falls in love with Shi Kyung, and for him she becomes a human being and begins to live at the In Gyeo House. The house is for people who are preparing to land their first jobs. To permanently become a human being, Ha Ni must make Shi Kyung love her within 100 days.