[Rough summary] A biologist studying a perverse merman boss is devoured and used up.
[Serious summary] Desharow, a biology student, travels to Iceland with his mentor to study mermaids for their research project. They capture a mysterious black-scaled mermaid without realizing that they have become prey themselves. Desharow falls into a deep abyss as he steps into the mermaid’s lair, becoming a feast for the merman. Later on, as everyone arrives at a mysterious island, a shocking conspiracy dating back to World War II is revealed. Desharow discovers an incredible connection between himself and the black-scaled mermaid, and realizes that he has undergone some kind of mutation in his body…
PS: Please note that this story leans towards reality, and the protagonist is a student who gradually becomes stronger as the story progresses. The story has a strict 1V1 route and will not include any non-consensual or childbearing settings in any extra works!