In broad strokes, the main character is a warrior who wants to gain control of the full kingdom ruled by the heroines.
After that very vague introduction, you kind of know what to expect. You can fairly see what kinds of personalities the heroines will have based solely on their outfits/jobs, and if you played some of the company's other titles you may know that there are different routes and some bad endings ones.
But as simple as this sounds, I feel that this title really nails everything that it sets out to do. If you have your eye on one heroine I would recommend you get this as you won't be dissapointed. Voice over is great, and the relationships grow gradually.
In terms of CG there is built "route viewer" to make it easier to unlock them.
It is also a fairly long game, if you want to check every route it may take you more than 20 hours.