Sister Q was a Japanese girl group on the Toshiba EMI label. They disbanded in October 2006 for uncited reasons. The members of Sister Q were three winners chosen out of 20,000 from the Smile Vocal Audition in 2003. Each girl went through extensive dance and vocal lessons until December 2004, when the group was officially signed to Toshiba EMI. Four months later, they made their debut with the single Night and Day, a Japanese cover of Frank Sinatra's song. It was used as the main theme song for the drama M no Higeki and became a hit with fans of the show. After releasing their second single Step One, a mini-concert and handshaking event was held in Higashimeihan for promotion. For their third single, the trio teamed up with Suzuki Osamu for their composition. Working Girl was released in March 2006 and Sister Q continued to gain fans. In addition to their current work, Masami was made the poster girl for the National Association of Commercial Broadcasters in Japan (NAB). Starting December 2006, she has been doing commercials advertising for commercials. It was announced in autumn of 2006 that Sister Q would be disbanding in October, with their last performance falling on October 16th. Their final show was sold out. Other artists performing included Nakabayashi May, Candy, Miyakawa Ai, and Mai. Despite being disbanded, their official site reported album containing all of their singles and other tracks was in the works; however, the official site and their Toshiba-EMI profile are both down.