My favorite harem manga/novel. I really like the MC because it actually feels like he CARES about the girls he meets. A lot of harem isekai with OP protags just seem to collect an army of women and he barely acknowledges their presence when they aren't doing something in that scene. in this, in one chapter he buys them all presents just because he can, because he cares about them, didn't think about getting something in return. I mean, he still did get something in return, but that's because they care about HIM. MC also helps the girls grow stronger rather than a using them as agoddamned cheering squad.

He is OP, but within reason because he once slew a demon king when he was a hero.
He doesn't spread modern tech not because he won't but he can't, do you actually think a guy who never finished 6th grade because he was summoned when he was 12 can spread modern tech willy nilly.

He not only cares about the girls, but also has the balls to cross the line not like generic MCs which are so indecisive, it is alright to call them walking v*ginas (cuz they're f*cking pussies)
It is generic, but enjoyable to read on your spare time to relax from the serious plot heavy novels