Japan Airsoft Laws
In Japan, airsoft guns are legal, but may not shoot with a muzzle energy above 0.98 joules.
Legal requirements are set on airsoft model manufacturers to prevent any possibility of a replica weapon being converted into an actual firearm.
Standards include (but are not limited to) use of low-melting point metals and non-ballistic plastics in structural components and incompatibility of mechanical components with actual firearm components and mechanisms.
The overall litmus test used by the Japanese National Police Authority is whether the replica weapon can be made to chamber and fire an actual round of ammunition.
These standards have proven successful within Japan, as it has been found that criminal elements discovered that it is significantly easier to purchase an actual illegal weapon in comparison to modifying a comparatively fragile replica into a functional firearm.
Due to this reality, most crimes involving a threat of physical violence are often perpetrated with edged weapons, as firearms seen in public are (by default) believed to be toys by the public at large.