What is this material?
It is actually a bolt of cloth. It's just cloth, like you would find in a fabric store...but it's "Segasonic" so it's extra cool. This was likely made to be used for fun home craft projects. You could make pillows, curtains, do quilting, or even a dust-ruffle for the bed. It is mostlly black, but with bright aqua line art of Sonic in various classic poses, including uncommon ones like 'looking out' and 'sneezing Sonic'. These are scattered with star bumpers, face logos, 'segasonic' title cards & circles/shapes. Also around the cloth are large 'medallion' type designs that are full color. You get Sonic in the winged ring, and finger-waving Sonic over a title card.
When cutting the fabric to use, you'd isolate one of these designs to feature it in the middle of something (most likely) like if you were doing a pillow or a cloth carry-bag. The background areas seem busy, but they're for smaller projects/to make sure you get plenty of Sonic on your item. This unused portion of fabric is interesting to see & likely to also be rather uncommon.