Nagao is best known for his photograph of
Otoya Yamaguchi assassinating Japanese Socialist Party politician
Inejirō Asanuma. At the time Nagao was a cameraman working for
Mainichi Shimbun. Hisatake Abo, Nagao's picture editor, told Nagao to cover a debate at Hibiya Hall. As Yamaguchi charged Asanuma, Nagao changed the focus to fifteen feet from ten feet. Nagao won the 1960
World Press Photo of the Year award and the
1961 Pulitzer Prize. The first award allowed Nagao to travel abroad widely, impossible for most Japanese people at the time. Nagao left the newspaper in 1962 and became a freelance photographer. ==Death==