The story will take place in a small kingdom. Said place had recently gone through a terrible drought that would've starved its people if not for the Baron taking a huge loan from the Associate of Merchants, a multinational guild that acted as both a bank and a gold lending organization. Five years had passed and the king was pretty much in the red, unable to even pay the obligated interest payments. thus threatening a foreclosure of his territory. Indeed, the Associate was no mere guild. It had its own territory that it had purchased or obtained off the various kingdoms and empires of the world. It didn't help that the king himself was currently bedridden, with his wife dying of childbirth many years ago. Now the princess was forced to do his work in his stead.
Here's where you come in. You would help her with your knowledge that could perhaps increase the coffers of the kingdom. Or perhaps even bargain directly with the Associate. They would love to obtain your wisdom as well after all.
How you come in the first place is up to you. You can just suddenly appear inside the princess' bedroom. Or you can be a traveler that was kicked out of the summoned hero's party due to not having any cheat abilities.
The world overall is a pretty crapsack one. Most people live in poverty with only a few middle class and upper class. Most ruling classes don't care much about the peasants, viewing them as mere tools, either to keep their life of luxury or to wage war. Slavery is widely practiced, with the Associate being its most ardent supporter. The Associate is also benefiting greatly from the war economy going on while they remain neutral. And most technological advances are produced and owned by them, that they won't share without a steep fee.
I prefer the rp to contain heavy ecchi as well as harem elements, though this point is negotiable.