In 2003 Sayumi Michishige has joined Morning Musume same band with popular girl group like Eri Kamei, Miki Fujimoto and Reina Tanaka, which all made their debuts with Morning Musume in the group's nineteenth single, Shabondama.
Since 2005 she was assigned as mentor to 7th generation member Koharu Kusumi.
Michishige uses to identify herself with phrase "Usa-chan Peace" (Bunny Peace) While saying "Usa-chan peace" she holds her index and middle fingers in V shapes next to her ears.
