It appears that Funamusea is a copyright tag for original characters by Mogeko (okegom) that don't appear in any of his other games. I don't know why it exists, it seems they should just be tagged original.
From what I remember, many of their original characters are eventually going to be implemented into various stories/have been implemented into various stories. I believe this copyright exists as a "purgatory" of sorts until these characters are eventually sorted out.
Mogeko's original characters are well known and everything, so I'm guessing that's why the copyright tag was created. Their website even has an index of them, if I'm remembering correctly? But maybe that was changed.