Congrats on picking this up. Have to admit I considered bidding on it. Seems like a pretty damn good deal considering the gem hiding inside the Hucard slot. Would love to see more info once you get it in your hands.
The custom HuCard was what convinced me to bid, but after thinking it through later on, I realized that I shouldn't have bid so much as it had to just be a either a regular Genjin 3 rom or a slightly hacked one. I just didn't want this to get snatched up by a prototype hoarder and never know exactly what it was.
I got everything today and tested the game. I don't have much experience with the Japanese version, but it seems to be the same as the retail version. I played past the first boss and didn't get any screen flashing or other indications that I needed to insert more credits. I'm guessing that that stuff is handled on the hardware side. But it still doesn't explain why they bothered to make a custom HuCard. Maybe the ending or some other parts will have some Korean text?
The HuCard looks much nicer in person. It's actually a very stylish black card with neatly placed eproms(?).
It'll be a while until I can shoot all the footage and put together the video I have planned, but I'll take some photos and post them soon to show everything in detail.