2003, Michishige began appearing in the show , as a regular with ex-Morning Musume member Yuko Nakazawa. 2004 saw her first appearance on an album, Best! Morning Musume 2, and in a movie—. During the summer, Michishige appeared in her first solo photobook and was placed in a temporary unit called Ecomoni with fourth-generation Morning Musume member Rika Ishikawa. Originally, the goal of the group was to promote environmental awareness only for the duration of the festival, but their popularity led to the members being cast as voice actors for the fourth Hamtaro movie—along with Hello! Project soloist Aya Matsuura, with whom they also released the main theme for the film, titled —and appeared in subsequent festivals. In 2005, Michshige and Rika Ishikawa released a duo photobook titled . Michishige also appeared as a regular news anchor on Hello! Morning for most of the second half of 2005. That year, she was assigned to be a mentor to seventh-generation member Koharu Kusumi, with whom she formed a duo called Rainbow Pink in the beginning of 2006. Introducing themselves as "Shige-pink" and "Koha-pink", the group was featured on Morning Musume's seventh album, Rainbow 7, with the song , and subsequently on the 7.5 Fuyu Fuyu Morning Musume Mini! and Sexy 8 Beat albums, with and , respectively. Following in fellow Morning Musume member Miki Fujimoto's footsteps, Michishige began hosting a radio show titled in October 2006. Running approximately 30 minutes per episode, Michishige's show consisted of her answering fan mail and participating in several games, among which saying a given phrase/expression in reverse, and giving general advice to her listeners. Michishige's second solo photobook, titled , was published on January 15, 2007. Shot in Okinawa, the book featured school uniform, swimsuit, simple one-piece, and wet yukata/bathrobe shots, in an attempt to convey a more mature image of the seventeen-year-old idol. Michishige also starred in , an original internet drama created for the purpose of advertising the Family Restaurant chain , as , a novice waitress training under the supervision of her seniors (played by Morning Musume's Ai Takahashi) and (Reiko Tokita). On June 9, 2007, Michishige began co-hosting the Young Town radio show as a result of Miki Fujimoto's Friday magazine scandal and subsequent resignation from Morning Musume. Shortly thereafter she released her third solo photobook and DVD, 17: Love Hello, both shot on the island of Guam. Her fourth solo