Following the Japanese ship-naming conventions for aircraft carriers, "Ryūjō" was named "Prancing Dragon". The ship was laid down at the Mitsubishi's Yokohama shipyard on 26 November 1929. She was launched on 2 April 1931, towed to Yokosuka Naval Arsenal on 25 April for fitting out, and commissioned on 9 May 1933 with Captain Toshio Matsunaga in command. While training in mid-1933, her initial air group consisted of nine Mitsubishi B1M2 (Type 13) torpedo bombers, plus three spares, and three A1N1 (Type 3) fighters, plus two spares. Matsunaga was relieved by Captain Torao Kuwabara on 20 October. After the Tomozuru Incident, the ship was reconstructed from 26 May to 20 August 1934.