This is called the "Sega Freaks Cards Set"...but other than 'cards' what exactly is it? The art here is nice and varied, some of it appears to be from the "Sonic Screen Saver" that was sold in Japan for a while. The backs of the cards all also have a smaller picture of something (not the same as what's on the front) as well as a larger word, & a bunch of text.

However, the text is all in Japanese, and this is all the larger the photo is, so there's no real chance to ever read it. Do write in if you know the deal with these curious cards! Is this all of them? What are they for? Where/how were they released? They've got to be pretty uncommon because this is the first they've been seen (in 2016) yet are quite likely from the mid 1990s or so.