rhythmsoundmotion
Adventurer
isekai is the anime and manga where characters come from a different world and experience a foreigner in a strange land story. (There is a similarly spelled genre that is a whole lot more adult.) While some Isekai have themes of overpowered main characters others can have themes of slice of life. However these are not over arching tropes of the Isekai genre. And yes some Isekai works contain adult and gore themes (but they are far from representative or common.) I would say that knowing if an anime or manga is an Isekai one does not tell you much about its content. Maybe a similar example would be learning if a movie is an espionage genre piece (it only says a bit about the movie.)