In 2002, Kobayashi debuted as an exclusive model of Loveberry, a fashion magazine for Japanese low-teen girls and published by Tokuma Shoten. She modeled for the magazine until 2005. In the next year, Kobayashi transferred to Face Network Co., Ltd. (株式会社フェイスネットワーク) and also debuted as a gravure idol. Then, in 2007, she took part in a model audition for the Kobe Collection, or simply, Kou-Kore. Kobayashi became a finalist but without any prize. Also in the same year, Kobayashi joined Miss Magazine (ミスマガジン) and became a semi-finalist, from which she solely won the GyaO Prize. Soon afterwards, on July 31, she renamed her family name from Kobayashi to Uno, which derives from the president and CEO of USEN Corporation, Yasuhide Uno (宇野康秀). On April 1, 2008, Platica Inc. was independent from Face Network Co., Ltd., subsequently Kobayashi got to belong to Platica Inc. and she renamed her family name again back to Kobayashi. In 2008, Kobayashi participated in a model audition of the Kobe Collection and became a finalist again; however, she did not obtain any prize. Also in Princess PINKY Audition (プリンセスPINKYオーディション) of a fashion magazine PINKY, she became a finalist but received no prize. In late 2008, Kobayashi was elected as the 23rd Asahi Beer Image Girl, on which she served until December 2009. Thereafter, on April 1, 2010, Kobayashi transferred to Burning Production, K.K.