"Kimi no Shiranai Monogatari" (君の知らない物語, lit. "The Story You Don't Know") is a J-pop song by the Japanese band Supercell, written by Ryo. Supercell released it as their debut single in August 2009 by Sony Music. The title track was the ending theme song to the 2009 Bakemonogatari anime series, and the B-side track "Love & Roll" was the theme song for the 2009 Cencoroll anime film. A music video was produced for "Kimi no Shiranai Monogatari", directed by Hirohisa Sasaki. Lyrically, the song deals with an unrequited love.

This single was the first release by Supercell which did not use the Vocaloid singing synthesizer Hatsune Miku as the vocalist, as they had done for their debut album Supercell (2009). Instead, Supercell employed the singer Nagi Yanagi, a vocalist who had previously submitted cover versions of songs to the Nico Nico Douga video sharing website under the name Gazelle. The single peaked at No. 5 on Japan's weekly Oricon singles chart, and in February 2010 was awarded a Gold Disc by the Recording Industry Association of Japan for having exceeded 100,000 copies shipped in a single year.

During the production of the 2009 anime series Bakemonogatari, Supercell was asked to compose what would later become the ending theme song "Kimi no Shiranai Monogatari". It was already decided that Supercell would release their debut album Supercell in March 2009, which used the Vocaloid singing synthesizer Hatsune Miku as the vocalist. In place of Miku, Supercell employed the singer Nagi Yanagi, a vocalist who had previously submitted cover versions of songs to the Nico Nico Douga video sharing website under the name Gazelle. "Kimi no Shiranai Monogatari" was the first release by Supercell to not use Miku as the vocalist. Yanagi was chosen for "Kimi no Shiranai Monogatari" by Ryo, who had been a fan of her voice even before uploading his own songs to Nico Nico Douga in late 2007. Roughly the next day after Ryo uploaded Supercell's first song "Melt" onto Nico Nico Douga in December 2007, Yanagi uploaded a cover of her singing the song. Yanagi, who was herself a fan of Ryo's music, contacted him and the two talked about someday collaborating.

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