In 2002, Natsuyaki successfully passed the Hello! Project Kids Audition alongside the other members of Berryz Kobo.
Being a member of Berryz Kobo, she also participates in the band's weekly radio show Berryz Kobo Kiritsu! Rei! Chakuseki!.
In that same year, she was cast as a character in "Koinu Dan no Monogatari", however she did not have a large part due to her age. Many members of Hello! Project Kids and Morning Musume participated in this film.
In 2003, Natsuyaki was chosen to join the group Aa!, which consisted of another member of Hello! Project Kids, Airi Suzuki and was led by Morning Musume member Reina Tanaka. They released only one single: First kiss released on October 29, 2003. The status of the group as a recording unit is unknown, since they have not released anything since their single in 2003, but the original lineup "reformed" for live performances in 2007. In 2009, Aa! returned from hiatus, and because leader Tanaka Reina had left the group to form the unit High King with other Hello! Project members, Miyabi took over as leader of Aa!
In 2004, all of Hello! Project participated in a large shuffle group that produced one single, "All For One & One For All!". This song is considered one of the themes of Hello! Project.
In 2005 Miyabi became a member of Hello! Project's shuffle unit Sexy Otonajan. Like Aa! there are only 3 members, Miki Fujimoto from Morning Musume, Megumi Murakami from C-ute and Miyabi. They only produced one song called "Onna, Kanashii, Otona", translated meaning "Woman, Sad, Adult".
Miyabi then became a member of Buono! alongside two other Hello! Project Kids, Momoko Tsugunaga from Berryz Koubou, and Airi Suzuki from C-ute. The unit was officially announced at the Nakayoshi magazine Festival 2007 on July 21, 2007, at Tokyo's Sunshine City in Ikebukuro, and formed to sing both the opening ("Kokoro no Tamago") and ending ("Honto no Jibun") themes for the anime adaptation of the Shugo Chara! manga. Buono! continued to record the ending and opening themes for the first season of the anime. As of the second season, Buono! only recorded the ending themes, as the opening themes were handled by Shugo Chara Egg! and Guardians 4, two other groups formed for thesake of performing Shugo Chara! music.