September 20, 2006. Before October 2006, Shirota finished filming for his third movie, Heat Island, which was released on October 20, 2007, and is based on the book of the same title written by Kakine Ryuosuke. Shirota played Aki, a street gangster who moves around Shibuya (a district in Tokyo) causing trouble and accidentally obtains a large sum of money that belongs to a crime group; however, the money once belonged to an illegal casino operated by the Yakuza and both groups are after the money. After Shirota's run as Charles Lindbergh in the 2007 year-end Japanese production of the Take Flight musical, Shirota starred in the January 2008 TV drama, Koshonin – The Negotiator, portraying Mariya Kyousuke, a condemned criminal. Next, Shirota starred in Rookies, the successful baseball drama based on the manga of the same name by Morita Masanori, playing Kei Shinjo. The series first aired on April 19, 2008, and ended July 26, 2008. after 11 episodes. He would reprise his role as Kagurazaka Makoto in the 2008 Hana Kimi special episode. In 2009, Shirota starred in the made-for-television movie, Go Ape, reprised his role as Shinjo Kei in the feature film for Rookies – Sotsugyou, and co-starred with Haruma Miura in Samurai High School as the soft-spoken, Nakamura Tsuyoshi. He also reprised his role as Mariya Kyousuke for the second season of Koshonin – The Negotiator and the 2010 feature film release of Koshonin – The Movie. He is also set to be in the Japanese stage production of Elisabeth as Der Tod from August 2010 to October 2010. He also played Ryuji Danma in the 2012 live-action version of Great Teacher Onizuka. Shirota made his solo singing debut as "U" in May 2011 under Avex Trax, releasing his debut triple A-side single, "U/Heart of glass/Sisyphus". His first album is called UNO. For the Japanese edition of his solo debut album, BACK TO ME, Backstreet Boys member Howie D (aka Howard Dorough) sought out Japanese idol Shirota for one of the bonus tracks, "If I Say" which was digitally released as a single on October 12, 2011. With the D-BOYS Shirota joined the Watanabe Entertainment group, the D-BOYS in October 2004. As a member, he participated in photobook releases, stage performances, radio show hosting, event and meeting greetings, and filming variety shows. With the D-BoYS, he was featured in their first two photobooks, the self-titled D-Boys