I don’t think anyone in the US knows enough to call the assassin, Tetsuya Yamagami, “deranged.” It isn’t like we know anything about him other than he served in the JMSDF.
JMSDF???
The Japan Maritime Self-Defense Force (Japanese: 海上自衛隊, Hepburn: Kaijō Jieitai), abbreviated JMSDF (海自, Kaiji),[5] also simply known as the Japanese Navy,[6] is the maritime warfare branch of the Japan Self-Defense Forces, tasked with the naval defense of Japan. The JMSDF was formed following the dissolution of the Imperial Japanese Navy (IJN) after World War II.[7] The JMSDF has a fleet of 154 ships, 346 aircraft and 50,800 personnel.