"Monster-girl-island" is a combination of three elements, which are commonly found in various adult videos.
1. Monster: This refers to creatures that may be seen as scary, strange, or out of the ordinary. They can be humanoid or entirely different from humans.
2. Girl: In this context, it implies female characters that could be human or monstrous in nature.
3. Island: This term indicates a setting where the story takes place, which is usually an isolated or secluded location.
Combined, "monster-girl-island" implies a genre of adult content that features a storyline set on an island, inhabited by female monsters. The island could be a mysterious, exotic, or dangerous place, where these creatures interact with humans or other monstrous beings. The content may involve fantastical elements, such as supernatural powers, magical transformations, or unusual sexual situations.