Otogibanashi mo Raku ja Nai! Tenseishite Ima wa Majo dakedo, Akuyaku dewa Arimasen

Chloé has been reborn into a world brimming with the sense of fantasy. Making good use of the knowledge from her past life, she worked as a witch, running every last detail of a shop that sells cosmetics and medicine. But one day, a hard-faced but handsome merman named Ludvig arrives, claiming to be a messenger for his older sister and her apprentice. He informs her that the mermaid princess Sophie has run away from home and onto the surface, and requests that she search for her with him...! Chloé soon realizes that what's happening is a lot like the story of "The Little Mermaid", which she read in her past life. But when danger befalls Sophie, an international issue with the Kingdom of Merpeople arises, resulting in Chloé and Ludvig being charged with a crime... Thus, in order to protect her home, she has to carry out Ludvig's request and work to prevent the "Mermaid Princess" from ending up as a star-crossed lover!! Source: Frontier Works