Model guns are basically toy guns that are usually made of zinc-alloy or plastic materials to satisfy gun enuthusiasts who live in Japan constrained under the situation as described above.
Most model guns try to replicate the physical looks of the real gun counterpart, and some are even made to copy the internal mechanisms. However, in order to enforce the strict gun control laws, there are laws that restrain the mechanisms of model guns. Thus, model guns on the Japanese market are safe and cannot be converted into something that can provide firing power.
Usually model guns come with pseudo cartridges that can be loaded with caps to simulate gun fire as is usual in toy guns. Some model guns even incorporate short recoil and blowback mechanisms to simulate semi-auto and full-auto firing. There are also models that only support dummy cartridges that look like real bullets and cannot be used with caps.