@flannan I see. Yeah, I know of this. Also don't like it, as I don't use nhentai, I need to go there, see the number, then look for the work on the site I actually use.
But still, I thought it was something in the character, like a measurement or a value, something the kk image card would give or let me find out in it.
@TDSgaming that image can be used on the adult game Koikatsu, or the steam version Koikatsu Party, as a character card. It has in their code, besides the actual image seen there, all the data it needs to turn it into a custom character in it. Save for mods that may be needed. Most custom chars use the ones in manlymarco's HF Patch, which has the most popular mod pieces and plugins including uncensoring (but not a famous one called kplug, because it is incompatible with a few others it does have).
Most character cards have an image of the custom character, to give you an idea of how it will look in the game, but as you can see here it is not really needed.