I know that Paypal's policy is to not allow anything adult, but I've been able to do it with Enty... Also, you are correct, it's 800 yen, not 500 (I didn't have my coffee yet when I made that post).
The Enty version does have quite a few more stages and animations.
As for the catacombs area, it's not bugged. You need to go all the way downstairs and defeat three blue-skin muscle guys and then head all the way back upstairs to the cross to disable the barrier to the big boss. Once you do that, two different types of mummies-monsters pop up. After you backtrack downstairs you can jump over the two blue-skin muscle guys and head to where the boss is. Spam attacks on the new boss and you'll be given entry into a room with fairies (for rescuing), several succubus enemies, and a horde of new monk enemies. The passage that leads out from there splits into two parts; one going down to a dead end with single water-monster (same as the ones from the sewers area earlier) and another leading back to "old town". If you double-triple jump over the exit out of the cave leading to old town, it'll bring you to a new fat-man enemy that only beats Airi up. The tower entrance to the left of the new fat-man enemy leads to the 1hp challenge with the new "gunslinger" Airi costume. The previous location of the gunslinger costume was in the "forest" area to the right of "old town" in between the fly-monsters. There's still an entry arrow that pops up when you walk by it, but it's been moved to the above cave-area, so pressing "up" does nothing.
I highly encourage people to support this game if you can. Otherwise, you're still getting a free version of the game to fap to, which is pretty generous of the creator.
