akikan40
If you want a real wild horse of an answer for a world to insert him in, ...Gushing Over Magical Girls (Mahou Shoujo ni Akogarete). ...think about it, a softcore H magical girl world where the main casts are all girls... ...frankly speaking, an Akikan Protagonist (heck, any halfway decent harem protagonist) would basically have an all-you-can-eat buffet there. Isao is a 'good guy', so what better way to stop the fighting between the Magical Girls and the Evil Organization than by bringing everyone under his heel~?
what about Konosuba? There are many different creatures and races in this world, + the MC will be able to become an adventurer and increase his stats, and if he meets Aqua or Eris, he will literally be able to copy the DNA of God. And the level of threat in the world is not so high that an MC would die from some slime’s sneeze, but at the same time the world is still quite dangerous. And there are also quite a few beautiful girls there.