In 2002, Sugaya successfully passed the Hello! Project Kids Audition. Her debut within the Hello! Project world came with the premiere of the first Minimoni feature film, as part of 4Kids, a shuffles group formed exclusively for the movie.
In 2003, Sugaya starred in the movie Hotaru no Hoshi (蛍の星), as Hikari, a fragile elementary school student who, with the help of her caring teacher, has a chance to be momentarily reunited with her deceased mother and overcome her emotional problems. She also starred in the drama, Shonan Kawarayane Monogatari.
That year also marked her first appearance on Kōhaku Uta Gassen, as one of Aya Matsuura's backup dancers, during the 54th edition of the renowned NHK New Year program.
In early 2004, Sugaya became part of the newly formed group Berryz Kobo. Since joining the group, she has also participated in the band's weekly radio show Berryz Kobo Kiritsu! Rei! Chakuseki!.
She has also, like other Hello! Project members, appeared in the Musume Dokyu! segments, namely episodes 39, 40, 54, 55, and 56.
Additionally, Sugaya has done a commercial for the Nihon Shokuniku Shōhi Sōgō Center in October 2003.
In August 2006, Sugaya was interviewed by MC Maki Goto in the 12th installment of the online only show Hello! Pro Hour. She later re-appeared alongside Momoko Tsugunaga on the 20th and final episode.
On October 12, 2006, Sugaya became the first member of Berryz Kobo, and the youngest of all the Hello! Project members, to release a solo photobook. Even prior to its release, the photobook was met with mixed feelings both by Japanese and overseas fans. Sugaya herself admitted, in an interview with Sanspo.com, to initially having doubts regarding the photoshoot, but claims to have had a pleasant experience and hopes her fans enjoy the various facets of her personality.
On December 31, 2006, Sugaya once again took the stage at the 57th NHK Kōhaku Uta Gassen as a backup dancer in Morning Musume's performance of Aruiteru, along with the remaining members of Berryz Kobo, Country Musume and C-ute.
In mid-2009, Sugaya became a member of new unit Guardians 4 which sang for the anime Shugo Chara!.
In 2017, her group Berryz Kobo had announced a hiatus, and then disbandment. Later, Sugaya announced her marriage and pregnancy to the world.