Here's something that hasn't been seen in a while: A Calendar.
Japan used to be really big on Sonic calendars...and, they are a good idea because who doesn't want an excuse to look at Sonic every day? This is most likely a special promotional calendar that was available at Japan 7-11 stores. It might have been a "buy and get", or maybe even a win-able. It's one of those large single page types with all the months just small at the bottom.
The top has "2018 Calendar" (in English, for some reason) & the middle is divided between the hero side at the top, with Sonic & heroes, while the logo and a line splits it. The bottom has the villains which include Metal Sonic, Chaos 0, Zavok, Shadow, Eggman, and of course, Infinite. There doesn't seem to be anything 'Sonic' about the calendar part itself there at the bottom. However, even when it goes out of date, it becomes a decorative poster. Because it wasn't technically 'sold in stores', but is instead a promo, it is likely to be uncommon.