I Picked Up a Wishful Mermaid.

"Show me how you make babies." Nina is a mermaid who has longed for the world on land. She took drugs to grow legs so she could interact with humans and learn how they live, but no one has taught her anything about sex. What is it about sex that humans find so fascinating? Nina desperately wants to find out, so she asks a handsome male-host who had found her while camping in the forest. Two people from different worlds gradually become attracted to each other in this melancholic fantasy love story. (Source: Bebe, translated)