Looks like one of those Digicon target shooter thingies (or a spin off/variant thereof), if it is you got the bargain of the year, while they weren't expensive when they came out bout 20 years ago, high FPS got them quickly banned in Japan, so the limited numbers got a cult following that pushed the prices sky high.
Edit. Didn't know about the maruzen version (& copies), with 5 shots I'd be looking at building a funky sniper project (I'm old enough to be allowed to say funky😜)