You chose Japan as the analogy. Japan allows virtually no guns. That is not what is on the table here.
Further, as I crudely noted, all of Japan's crime rates are hugely lower than ours. Their society is in nowhere near the state of moral decay that ours is.
Want to take a guess as to their rate of "flash mob" crime ? How about arrests for playing "knockout" ? Those crimes have nothing to do with guns.