While in an antique shop in Japan ages ago (with a weird attached cinema) I bought the shop out of these old coin slabs. For the life of me I can’t find any solid examples on the internet like them. I can see other examples online with the coins (they’re Meiji), but none with the slabs nor the box that contains them in the last picture.
If anyone knows anything about them or is interested feel free to tell me. A bit of an enigma at the moment.