Bunny Black is a VN and dungeon crawler by SofthouseChara, a company known for complex and well-designed game systems based in fantasy worlds.
Bunny Black is one of their earlier games, and it is a lot more focused on the actual gameplay than the story. However, the gameplay is actually quite well-designed, with the ability to purchase monsters to serve as the other members of your party, the ability to choose how you will advance Darcs (the protagonist), and a mission system reminiscent of many other games of the type, where you go to the bar/item shop and take on missions to advance yourself in rank, explore the dungeons, and obtain items and money. To be honest, this game requires a ton of grinding for the early part of the game, both to obtain the rank necessary to use more powerful monsters and the levels necessary to survive battles. However, once you reach around level 35-40, and have a solid party, you can enter the dungeon known as the 'Gate to the Demon World', a dungeon that has rest spots and high-experience enemies to allow you to power level your party to whatever level you want them to be. At that point, it is possible to get up to level 70 in a matter of about four to six hours, if you hunt efficiently (if you were smart enough to get the skill that increases gained experience). That will let you complete the game, with ease.
A more problematic aspect is the story... what there is of it. To be blunt, this game's 'story' is almost all about the gameplay and the ridiculous number of H-scenes (about 70% of them about raping adventurers and other female enemies) included. The funny thing is that the supposed primary heroine, the Maou, is the flattest character in the game, up until the end. Sad... that they didn't manage to inject the same level of storytelling quality seen in Ouzoku.
A few pieces of advice: This is not a game to be taken on lightly... be prepared to die a lot at first, as you get used to the gameplay. Also, this game consumes an immense amount of time, (fifty-five hours total for me) meaning you probably will not be able to finish it with even reasonable quickness. There are very few decent healer monsters, so you'll probably end up having to use Darcs that way, by accessing the healing skills (he can use them all, if you use his skill points that way). Moreover, since he is the most over-powered ally in the game, you'll probably end up using him as a frontline fighter as well (he absorbs damage way too well). I'd suggest you get the first level of the treasure-box opening skill and the identification skills, as not having these will be a huge drain on your funds otherwise. My final party formation had four sorcerer monsters, two long-range monsters, and two frontline heavy-hitters... Most of your party for most of the game is going to be made up of sorcerers or front-liners, because of the number of early enemies you'll barely be able to damage with regular attacks. Sadly, if you try to go the other way, you'll probably never get anywhere.