About two weeks after finding the last piece of this, in a whole different thrift shop in a whole different city, this is what I found yesterday:
Isn't that funny? Apparently it's some sort of style of making ceramics like this, creating figures of several seperate parts combined. This set has four cups that can all be part of the teapot, the faces have their eyes either open, half open or closed.
And look, it gets even more peculiar... I found this as well:
A large mug with a clown on it wearing exact the same outfit as the boy on the breakfast set I found earlier. Only the colors are a bit different, probably cause the clay that the cup and mug are made of seems a bit different. In general I'm not fond of clowns at all (usually I think they're scary), but this was so funny that I brought this one home as well. To be honest I really don't have room for these anymore, so I think I'm going to sell them in the little online vintage shop that I still hope to open someday. I'm not sure how to do that yet: maybe I'll just add a little vintage department to my current etsy shop, maybe I'll start something new... But till that time I just enjoy these!
By the way the teapot set obviously seems to be Asian (or at least Asian-inspired), and someone earlier told me that this type of ceramics is from Japan. Anyone who knows more? I'd love to hear!