the theme song for the film Judge!, starring Satoshi Tsumabuki and Keiko Kitagawa. Sakanaction produced an original song for the film's ending credits, "Eureka", which was released as a single in 2013. The single was released digitally exclusive to iTunes on July 7, followed by a wide and physical release on August 4. The single was released in two physical versions, CD only and CD/DVD. The DVD edition featured a recording of five songs taken from the band's performance at Shinkiba Studio Coast on May 15, 2010. Yamaguchi and the other band members wanted to add the DVD to the single, as they felt that "Identity" was single made primarily to introduce people to Sakanaction, so felt that a DVD showcase of their most recent concert was appropriate. The concert was later released in full as the Sakanaquarium 2010(C) DVD on February 2, 2011. The first press edition of the physical single came with additional photos of the band during recording sessions and concert performances, and a serial number to apply to attend the band's Sakanaquarium 21.1(B) concert at the Nippon Budokan, held on October 8, 2010. The single featured two additional tracks, the B-side "Holy Dance" and a remix of "Yes No" from Kikuuiki created by Aoki Takamasa. Conceptually, Yamaguchi thought of the single as a piece of fruit, with "Identity" acting as the skin, "Holy Dance" the flesh and "Yes No (Aoki Takamasa Remix)" the pit. In August 2015, a new version of the song produced by Emi Kusakari called "Identity (Ks_Remix)" was released on the band's compilation album Natsukashii Tsuki wa Atarashii Tsuki: Coupling & Remix Works. The album also compiled the single's B-sides "Holy Dance" and "Yes No (Aoki Takamasa Remix)", and a music video was created for "Holy Dance", directed by Yamaguchi personally. On March 3, 2016, Kanna Hashimoto of the girl group Rev. from DVL sang a cover of the song at an event to promote the film Sailor Suit and Machine Gun: Graduation (2016), which she decided to perform because she believed the song's lyrical theme of self-identity matched her experience of the film. Since its release, the song has become a staple of the band's concert set-lists. Five recordings of performances of the song have been released. The first was at the band's performance at the Nippon Budokan on October 8, 2010, was released as Sakanaquarium (B). The song features on the