Having defensive protection is ludicrous to be cautious of selling to civilians. Its not illegal to have body armor either yet it is treated similarly. Shame on you, its not an illegality, sell to anyone who wants it.
Due to the war in Ukraine, there is no guarantee that communist, socialist, or religious terrorism will not occur in Japan, so police vehicles like this are necessary. It would be great if they could convert it to right-hand drive for Japan.