I think this fanart is related to Tomytec's Little Armory guns.
Considering that Daito is the official illustrator for the Little Armory toy line, I'm sensing that this is some kind of Feelies for an upcoming promotional event.
Note: All the wares shown here (including the gun rack backdrop) are Little Armory wares, some of which have already been released and have since sold out (at least on Amiami).