I haven't played the prequel of this game and you don't really need to (though I'm sure it will give a lot more background info on the female characters) to enjoy this game. I really like how well fleshed out each characters are. It's not the typical "1 - 2 characters have a personality with the MC, but the rest are in the background". All of them truly are great. And the author really was able to make the "cultural shock" apparent. That's how a good "isekai" should be, though it's isekai for the FMC in this case.