Oh tools don't do anything. That's why civilians can have tanks, LMGs, grenades and bombs. That's why tools capable of indiscriminate carnage in the hands of "bad guys" aren't restricted. But for some reason nothing will convince you assault rifles belong in that category.
Go polish your red dot sights and prepare for when you "need" it for "self-defence". I mean shit, if I had to react to someone carrying a somewhat unwieldy assault rifle indoors, I think I'd much rather try to quickly draw a pistol than unsling a rifle.
Yes, japanese law enforcement carry pistols. I think law enforcement should have access to firearms, but then I don't have a weird paranoia that my own goverment will suddenly start oppressing it's citizens and I'll need a rifle to stop them. Also, the Japanese police force have discharged their firearms as many times in the last decade as single state PDs in the US do in a single day. Because, as for japanese criminals, the police use guns there as an absolute last resort. Rather than, say, unholstering their weapon for every traffic stop.