>>2895387I looked into it, and I'm convinced that the "original" tag you mention is simply referring to the fact that it is an original work by that artist.
I translated the chinese text in the title and the description, and I got "one year later" and "postcard on the back". Now, I have no clue what the latter is supposed to mean, but "one year later", given the rest of the setting, is a pretty good indicator towards it being Yui.
