Here's a red 'breifcase style' canvas Sonic school bag. It's a bit of an old-fashion design (rather than the usual backpack) & is genuinely from the 1990s in Japan. It has a red thick carry handle for the top & big Sonic art by Naoto Oshima on the front with some rings. The SegaSonic logo is down one edge, while "Welcome to the next level" slogan is in gray at the bottom. Notice that they added the score / rings / time display in green at the upper right corner. The back has adjustable straps. When you open it, you can see the squeeze clips that keep it shut & that it has a plaid pocket inerior. It also has a student ID holder, 3 dividers inside & a zip pocket.
The material is really sturdy & thick nylon canvas type stuff. The bag is thought to be from 1991. The inset has the small plush Sonic sitting near the bag and it is on top of the deluxe Mania bonus box, so you can tell how big it is.