I've been playing futanaring for the past few days now. I haven't beaten the game yet, but I've been hunting for the CGs on page 2 now that I've gotten all the Sealed Magic stats where I want them.
I've figured out that the two CGs whose hints are "Hostess Club" actually refer to the Strip Club. If you get a perfect round on Easy and Medium, you unlock a scene (for each). I haven't managed to no-life myself a victory in the Hard or Extreme modes yet, though, and I'm nearing my breaking point, especially considering there are only two CG scenes that say "Hostess Club", so whatever reward you get for beating stages 3 and 4 could actually just not be worth it...
While I'm posting about this game, I just wanted to throw out some very helpful tips. First, you can tell if an enemy is capturable by bringing up their character page by double-clicking on them on the field. If an enemy is NOT capturable, you can still steal their items (using the Steal move) if they have anything really good. For example, a certain boss carries a sword that gives +6 Attack and +1 Defense.
Additionally, /all/ enemies give +3 sealed magic experience when you capture them. If you want to grind for those points, it doesn't matter even a little where you do it.
Finally, there are some enemies that are capturable but super rare, possibly even one-time-only. I recommend saving before every mission, and always trying to capture at least one of each new enemy you see. Chests can also be found in levels, especially dark levels, and they might not be there on a re-visit.
Anyway, that's all I've got for now, if you've got insight into this game, please contribute.
PS: Actually, one more tip. The chevron next to the lock on your character screens determines whether or not they counter attack when hit by an enemy within range. If you don't want your characters to KO something you painstakingly weakened for capture, then turn off their counter attack.