Not sure if I shared this before, but I am working on documenting the undocumented. The current Japanese baseball card guide (an amazing piece of work spearheaded by Gary Engel - order it here:
https://www.prestigecollectibles.com/vintageguide.aspx) is still only a partial list of all the amazing Japanese menko cards that are out there. I've created a blog to organize pictures of all the menko I come across that are as of yet uncatalogued (and which I'll pass along to Gary). Feel free to share any you find here, and I can add them to my blog at:
https://japanesemenkoarchive.blogspot.com/