"Stay Gold" is a song by Japanese musician Utada Hikaru. Used in a high-profile campaign for Kao Corporation's Asience shampoo commercials in 2007, the song was released as a double A-side single with Utada's song "Heart Station" on February 20, 2008.

In February 2007, Utada released "Flavor of Life", the theme song for the drama Hana Yori Dango Returns, which became one of her most commercially successful singles, selling over eight million downloads and becoming the second most digitally successful song of 2007 globally. This was followed by a second single in 2007, featuring the songs "Beautiful World", the theme song for the animated film Evangelion: 1.0 You Are (Not) Alone, and "Kiss & Cry", a song used to promote Nissin Foods' Cup Noodles.

On December 7 to celebrate the start of her 10th year since her debut, her song "Automatic" (1998) was released as a free ringtone for four days. At the same time, it was announced that Utada was working on her fifth Japanese studio album, to be released in spring 2008.

The song was first announced and used in Asience commercials in October 2007, and released as a ringtone on December 7. After a single month, the song's ringtones had been downloaded more than 250,000 times.

After the song was released to radio stations on January 7, it was heavily played on FM radio stations across Japan. It managed to reach number one on the newly established Billboard Japan Hot 100 chart in mid January, despite having no purchasable release at the time.

In February, Utada was featured in many music and fashion magazines in Japan to promote the single, including issues of Pia, Patipati, CD Data, What's In? and Pop Teen. On February 28, Utada performed the song live on Utaban. It has been part of two of Utada's concert setlists: her international tour Utada: In the Flesh 2010 and her two date concert series Wild Life in December 2010.

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