Guns are banned in japan or they are strictly controlled. I heard one point that even a police guns have no bullet in the first chamber. This does not mean Japan has no mass murders ... just guns are not often used.
Oh by the way, Japanese swords are not permitted either. Did you know that?
So, if you are visiting Japan, DO NOT BRING YOUR KNIFE!!!
Any fixed knife containing a blade length of 15 cm or more requires permission from the prefectural public safety commission in order to possess. Permission requirements also apply to any type of pocket knife over 6 cm (including Automatic Knives), spears over 15 cm in blade length, and Japanese halberds.[32] All knives with a blade length over 8 cm are prohibited from being carried, under a crime law,[33] with an exception for carrying for duty or other justifiable reasons. Possession is considered a petty crime and is not usually punishable by prison time. However, in cases where assault occurs with the knife, there is a penalty of up to 2 years prison or up to a ¥300000 fine. Folding knives with a blade length less than 8 cm (such as Swiss Army knives) are permitted, while SAK with a lock blade are prohibited from being carried.