Here are some bonus items for the release of Sonic Boom Fire & Ice, but only in Japan. But...why aren't these on the "Boom Gear" page?
Because they've got nothing at all to do with Boom. They're all normal classic style items. There are acrylic mini Sonic arts which snap into a stand up base (see the little pegs on the bottoms), another crystal cube & a 25th Anniversary mug.
Why release classic stuff with a Boom game? It's the only new game coming out during this, the 25th Anniversary year.

The stuff is actually really super! The mug has great design, the crystal cube is 3D and the acrylic pieces bring cute & fresh new art! As a bonus-item-only all the items are likely to be rare, & the good design will ensure it's all desireable.