G-Men '75 was a long-running prime-time television detective series in Japan. It aired on Saturday nights in the 9:00–9:54 p.m. time slot on the Tokyo Broadcasting System network from May 24, 1975 to April 3, 1982. A sequel, G-Men '82, followed, as did various specials. With several updates and cast changes, it included 355 episodes. The story revolved around an investigative organ, the G-Men. The principal character, who spanned the entire series, was Superintendent Kuroki. Portrayed by Tetsuro Tamba, Kuroki directed the members of the group. The original cast also included Yasuaki Kurata as Detective Kusano, trained in karate. Gō Wakabayashi joined in Episode 105, and remained to the end of the series. His character, Lieutenant Tachibana, replaced a detective who was written out of the script. Many more actors and actresses took regular roles in the series over the years. Gō Ibuki, Maria Mori, Mari Natsuki, Hiroshi Miyauchi, Takeshi Kaga, Bunjaku Han, and Kyōko Enami were among them. Shunsuke Kikuchi wrote the opening theme songs. Various artists, including some cast members, wrote and performed the closing songs. Among the actresses who sang were Mari Natsuki, Bun-jaku Han, and Kyōko Enami. For most years, the lyrics were by Junya Sato, set to music by Shunsuke Kikuchi. Veteran announcer Takayuki Akutagawa narrated the series.