Similar to Ikinokori Renkinjutsushi wa Machi, the fifth Koushaku Reijou no Tashinami book marks the main storyline’s conclusion; later novels tell a prequel story focused on the protagonist’s mother.
The series begins with what I now have to assume is a common otome game setup: A prince’s fiancée is brought before him to answer for crimes against his girlfriend. This is the fourth time I’ve seen it now (Mobseka, Tensei Oujo to Tensai Reijou, & Kangoku Slow Life being the previous three) and so far each implementation has been slightly different.
From there it quickly transitions into an ‘introduce modern concepts to a fantasy world’ type of series before eventually dipping into conventional romantic developments.
Personally I’d have to say that the first three books are the best, with the fourth and fifth suffering from being a bit too laden with preachy monologues and overly convenient event developments. While it’s true the protagonist always had an abnormally easy time implementing her policies locally, the way she ends up effectively bulldozing through on a national level as well (without even trying to) heavily strains credulity.
Still, it’s a pretty fun series all in all. Just don’t expect much in the way of believable conflict.