"Rookie" (Japanese: ルーキー, Hepburn: Rūkī) (Japanese pronunciation: [ɾɯ:kʲi:]) is a song by Japanese band Sakanaction, released as their second single from Documentaly in March 2011. The song was stylistically different from the band's previous singles, featuring a strong electronic dance music sound, which reviewers in Japan praised for its tenacity, and its fusion of dance and rock music.

The physical edition of the single was released five days before the 2011 Tōhoku earthquake and tsunami, which caused a delayed release in many regions of Japan. Much of the promotional activity was cancelled or postponed, with vocalist Ichiro Yamaguchi preferring to focus on raising spirits during radio interviews over promoting the song.

After the release of the band's fourth album Kikuuiki in 2010, led by the single "Aruku Around", Sakanaction performed a thirteen-date national tour of Japan in April and May of the same year, Sakanaquarium 2010 Kikuuiki. At the tour final on May 28 at Zepp Tokyo, the band performed a song entitled "Identity" for the first time during the concert's encore, a song that had first been written early in the Kikuuiki recording sessions in 2009, and recorded just after the band finished recording music for the album. On the same day, the song was announced as the band's next single, scheduled for release in August.

The single was well received by music critics in Japan, praising the work for its upbeat arrangement incorporating Latin percussion. Commercially, the single reached number twelve on the Oricon singles chart. This performance was better than the band's 2008 single "Sen to Rei", however the release under-performed compared to 2010's "Aruku Around".

...
Wikipedia