6 more tees from the Sega Shop & they're for Mania Plus.
Sonic Mania was a real success, so Mania Plus added even more fun with Mighty the Armadillo & Ray the flying squirrel. The Sega Shop added tees to celebrate the game. The first & second shirts are variants. The first is white, the second a dark royal blue. They have the character art (fully shaded) for Mighty, Ray, Sonic, Knuckles & Tails, all kind of overlapping for a colorful design. The next 2 shirts are also variants; one royal blue and the other black. This has the Mania Plus 'box art' (game never had a box, it was a digital download) with the added characters & a geometric background.
The middle tee is Knuckles themed. It has classic Knuckles' forward-facing neoclassic face & his chest crescent shape stripe...but that's it. No outline for the body or anything else. This is an unusual choice of something to do for a tee, but it doesn't look terrible. The last shirt is all white, with tiny Sonic, Tails & Knuckles classic solid color faces all in rows, all over it. It almost falls in the 'secret-Sonic category because it's not apparent what they are at first glance. Each of these is about 26 dollars, and is a late 2018 - 2019 item in the SegaShop.