Some sexual slave stories are based on historical facts, which serve as a form of documentation of the atrocities that occurred in certain historical periods, such as during wars. However, there are also fictional sexual slave stories in literature or movies for the purpose of creating plots. But we must always be very sensitive when dealing with such topics, especially those related to real historical events, as they represent great human tragedies.
Well, it's hard to say for sure. The concept of 'porn-like' is quite subjective. Some might consider certain novels with excessive sexual descriptions as such, but it depends on individual perspectives and cultural standards.
In many places, 18+ porn comics are considered illegal. This is because they can have a negative impact on society and violate moral and legal standards.
The main distinction of porn with a story genre from regular porn is the presence of a coherent narrative. Regular porn often jumps straight to the sexual action, while the story genre tries to add some kind of story framework around it. But in the end, both are adult-oriented and feature explicit sexual content.