I was really disappointed to hear about this today. Seems like this is happening more frequently in Japan lately although i cant say its become a serious problem but its definitely become more high profile in which these things happen. Im posted it here since the title of thread was whats bad in Japan. Keep mind this could happen anywhere not just Japan. I thought it would make for an interesting read.
Woman goes on stabbing spree in Japan - Asia-Pacific - MSNBC.com