Sōryū (Japanese: 蒼龍, lit. Blue (or Green) Dragon) was laid down on 20 November 1934 at Kure Naval Dockyard, her construction taking 13 months. She was launched in late December, 1935, and passing trial successfully she was commissioned in December, 1937. She was one of the first carriers to be built from the keep up as a carrier and established the basic format for all future Japanese carrier classes, not a converted battleship or battlecruiser; she incorporated lessons from the Ryujo and other carriers.