It's a myth to think that guns don't exist in Japan. Both the police/military AND the organized criminal elements (Yakuza) have guns, REAL guns from known manufacturers, smuggled in. So if the shooter had organized crime ties, he most likely would have used a reliable, multi-shot gun like a Baretta 92 or S&W, Colt, etc. That 2-barrel, 2-shot frankenstein homemade gun held together with tape... I'm amazed that it didn't blow up in the shooter's hands.