I hate how the author attempts to tell the reader how smart Yamai is via the queen by constantly having her be surprised by his intelligence. But he never really appears to live up to such high praise, at best he's sort of average and even that's a stretch.
This is a guy that had a whole month to prepare things to bring to this new world. A generator, some convenient electronics and a PC, yeah that's all great but then he just brings a bunch of shitty reality tv-shows and video games. Not a single thought like "Huh, their world isn't very technologically advanced, what if I brought all of our scientific knowledge along?".
He doesn't even have to Dr.Stone it, with a whole kingdom's resources, intelligent researchers and craftsmen at his disposal they could eventually get a fully functioning electrical grid going, and that's just the basics. He even lamented over the fact that his generator would only last 10 years but never thought about bringing the knowledge on how to build one.
Even basic stuff like chemical compositions, how to create/extract various materials or building techniques would all be invaluable. All he had to do was fill a few HDD's, maybe even some physical books as backup in case electronics got fried or something.
People have already pointed this out in individual chapters but I had to vent about it, got about halfway through current chapters before deciding I can't continue.