Alright, I'll be honest here. This is a parody of the genre, which means the plot isn't precisely juicy or anything too elaborated. But it's still one of the best within Isekai genre, if you let me.
It's a breeze of a reading, mostly funny and lighthearted. The author knows when to be serious and when to give bits of angst. She plays very well with the trope in all the possible ways and explores its possibilities. I'm surprised that she wrote it in her teens.
Just... Beware, if you're not comfortable with Master/Slave dynamics, masochism, torture kink, slightly erotic minor-adult interactions, gore, and a huge age gap in relationships, well... Just turn around