I've already finished Onikakushi-hen of the Higurashi VN. But now I have a reason to replay it thanks to this patch I found on /jp/.
What the patch does is basically take the original Onikakushi-hen and change it to look more like the Higurashi Matsuri PS2 port by incorporating the character sprites, CGs, music and voices from it.
One sight flaw to this patch is that it isn't compatible with the full game of Himatsubushi-hen I have installed on my PC. Which would normally result in you having to install the Onikakushi-hen DEMO to use it.
However, I discovered a little workaround so it'll work using my install of Himatsubushi-hen.
All I did was create a new folder in my higurashi4 folder. Copy the contents of the patch into it. And then copy over the arc.nsa, icon and default font files from the full game translation patch folder and that's it.
I can now run this patch as a standalone program without needing the actual DEMO itself.