"Irony" is a pop song by the Japanese duo and idol unit ClariS, written by Kz. It was released as the unit's debut single on October 20, 2010 by SME Records. The song was used as the opening theme to the 2010 anime series Oreimo. A music video was produced for "Irony". The single peaked at No. 7 on Japan's weekly Oricon singles chart.

In preparation for the launch of LisAni!, an anime music magazine published by Sony Magazines under Sony Music Entertainment Japan, the editors aimed to discover new singing talent to showcase in the magazine's debut issue. Kz was brought up early on as a potential candidate to compose a song for LisAni! due in part to his prior activity of uploading original music to the Niconico video sharing website. For this reason, LisAni!'s editors went to Niconico to discover a singer. After some searching for young singers on the website, music critic Akihiro Tomita who had been helping in the search came across covers sung by first-year junior high school students Clara and Alice, who were subsequently chosen to sing the song for the magazine. Tomita then approached Kz to compose the song for the girls' debut.

Kz and ClariS would go on to collaborate on two songs for LisAni! in 2010: "Drop" with the magazine's debut issue released on April 24 and "Kimi no Yume o Miyō" (君の夢を見よう^?) with the second issue released on July 24. During the production of the 2010 anime series Oreimo, the anime's producer Atsuhiro Iwakami became aware of ClariS via LisAni!. Iwakami took into account that ClariS' members were in junior high school, the same as Kirino Kosaka in Oreimo, and that their voices were very beautiful, so he thought it would be interesting to have them sing the opening theme song for Oreimo, which would later become "Irony".

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