Toshio Hayakawa (早川 俊夫, Hayakawa Toshio, January 7, 1948 – December 6, 2022), better known by his stage name Ichirou Mizuki (水木 一郎, Mizuki Ichirō), was a Japanese singer, lyricist, composer, voice actor and actor best known for his work on theme songs for anime and tokusatsu.

He was referred to by fans and fellow performers alike as the Aniki (アニキ, "big brother") of the anison, or anime music genre.

He signed to the Nippon Columbia label and released his first single called "Kimi ni sasageru Boku no Uta", composed by Kanae Wada, in 1968.

Robocon, Kamen Rider Stronger, Tekkaman, Steel Jeeg, Akumaizer 3, Chōdenji Robo Combattler V, Astroganger and Space Pirate Captain Harlock.

[2][3] Mizuki performed theme songs throughout the 1980s and 1990s, for shows such as Beast King GoLion, Getter Robo Go, and Jikuu Senshi Spielban, his work not as extensive until 2000.

He later reduced his membership in the group to "part-time", allowing for the entry of Hiroshi Kitadani (One Piece), Masami Okui (Revolutionary Girl Utena), and Yoshiki Fukuyama (Macross 7 as Basara Nekki's in Fire Bomber).

As a voice actor, he played the roles of Yoldo in the first episode of the OVA Dangaioh, Rat Hector in Coral no Tanken, and the villain Keisar Ephes in the video game Super Robot Wars Alpha 3.