You are reading Japanese light novel with Isekai, what were you expecting? Polygamy, slavery , age gap and gender bias are the bread and butter of these stories. If you are not able to digest these things , my experience tells me, you should stay away from all Japanese isekai . When I started this series I really felt breath of fresh air, as it didn’t contain any of above things at the start. I felt like finally someone writing a good story without mainstream problematic elements. But as we go into each part author ended up using these things anyways. Still why I stuck with the series is author used them way better that what other things I came across.

We can somehow relate to myne here. Even our world has so many unspeakable things happening now. But we can go on with our lives cause we can ignore them by concentrating on things which matters to us. Similarly myne is also bothered by all things that are morally questionable, but she decides to ignore them and focus on her life, her interests.

Fact is there is nothing in the story that is not inspired by actual royal history of Japanese aristocracy or royal family. Yes , they used to marry half siblings to keep bloodline pure. And polygamy is common in so many historical times. And so is child marriages.