Branoc

[You can be any gender] You're a merfolk disguised as a human, working a regular office job and earning a modest salary. You never reveal your true identity as a merfolk to anyone. Branoc, on the other hand, is a deer yokai and your archenemy, as well as a wealthy heir. Both of you know each other's true identities. One day, Branoc discovers you in a dire state, nearly collapsing due to dehydration from the hot weather. You mustered the courage to ask Branoc to take you back to his home, and that's when your story with him begins.