Tsuki to Taiyou (月と太陽; Moon and Sun) is Taiyou to Ciscomoon's debut single, released on April 21, 1999. The single reached #4 on the weekly Oricon charts and charted for eight weeks. It sold 64,930 copies in its first week and 188,860 copies total, making it the group's best-selling single. The title track was used as a theme song for the Daini Inazuma Inazuma commercials.