Mizuki Sano graduated from Fujinomiya West High School, and Shizuoka University with a degree in law. He has a younger brother, Daiki Sano, who is also an actor. The two main characters in the manga Hanazakari no Kimitachi e are named after him. Mizuki Sano joined Johnny's in 1991. In 1993, he became a member of the short-lived Johnny's unit J-Eleven and also a member of KinKi Jr., a back-up group for KinKi Kids. In 1995, Sano became a first-generation member of Johnny's Sr., along with Masayuki Sakamoto, Hiroshi Nagano, and Yoshihiko Inohara of V6. Until 1996 he was a back-up dancer for Hikaru Genji, V6, SMAP, and KinKi Kids. Unlike most of his contemporaries in Johnny's, Sano has neither graduated from Junior status nor left the management of Johnny's. He now mainly performs as a stage actor.