Several sites where you can find chara cards, scene data, and other stuff for Koikatsu.
If you are here then most likely you already know about this site, but anyway, here is the link to a large Japanese site where users upload artworks. You may find some really good Koikatsu chara cards and scenes there, backgrounds for a visual novel, and lots of other stuff. (Or you may just jerk off to the hentai pics uploaded there.) LINK
This site is a HUGE collection of chara cards and scenes for Koikatsu, Honey Select, Artificial Academy, and Custom Maid 3D 2. You may also upload your own cards and scene data there. LINK
Here you can also find some chara cards and scenes LINK