I just finished bunny black, it was actually pretty great. A good mix of all the elements and the combat/leveling system actually feels amazingly rewarding, my only qualm was the difficulty curve was a little imbalanced; it started out extremely difficult but ended up being a cakewalk, there was no real need to switch to second or third tier units (my first tier units just steamrolled everything including the last boss without any difficulty.) I played on normal, I would recommend anyone who picks it up play it on the hardest difficulty as the curve is a little wonky. It also has a new game + option (but it isn't necessary to get all the scenes, and doesn't really offer much in the way of new content.) Although Bunny Black was grindy for sure, the grinding felt somewhat rewarding as you are awarded scene variations and new dialog. As far as ero RPG games go, it was one of my favorites by far.
To the OP, another great dungeon crawler which may be lost to the annals of time is Words Worth, it is old but I feel like it is definitely worth playing if you can get your hands on an english copy and then get it working. The story-line is actually somewhat gripping, and even though there isn't as much ero content as Bunny Black, the cg that are included are very well drawn (I really loved the art style but the censorship can be somewhat off putting.), the story makes up for most of its shortcomings and actually feels like a somewhat epic tale of progression and growth. The gameplay is unique in that it plays out like a first person shooter/slasher (no turn based combat here.).
Be forewarned, it is quite grindy and the difficulty curve is extremely unforgiving (i.e: you will destroy one fight, then a few steps further you will encounter an enemy which will dispatch you in a few hits.)