Who is Tetsuya Yamagami, the man who assassinated Japan's former PM Shinzo Abe?

Former Japanese PM Shinzo Abe died after being shot during a campaign speech. Meanwhile, police arrested the shooter at the scene of the attack and a gun was recovered from the area. He was later identified as Tetsuya Yamagami. According to reports, the 41-year-old served in the Maritime Self-Defense Force for three years in the 2000s. Yamagami, reports said, was "dissatisfied" with Abe and wanted to kill him.