This is a perfect place to grind coins, Sumikowarashi (for the Special Unity towards Kisshouten) and Fire Wolf (for the Special Unity towards Nekomata) all at the same time [confirmed by and recommended by Zekeinferno/Izumi] The monster drops are also fantastic as they give 300+ exp each and they drop fairly easily.
If you have a high tier, OVERLY brushed, drugged (medicine), and / or +1'ed hime, you can solo this easily for a mere 2 / 3 AP. It's still beneficial to do this dungeon even if it requires a tad bit more AP. If you can get to this dungeon in the first place, which is after Fort of Axeman (lv. 13 requirement), you'll be able to clear it with ease.