The Mitsubishi A6M Zero was the main fighter of the Imperial Japanese Navy throughout World War II. It gained a reputation for being invincible early in Japan's participation in the conflict, with its maneuverability, range, and climb rate unmatched by any Western fighter, whether land-based or carrier-based. It was also the aircraft used by both Hiroyoshi Nishizawa, the greatest Japanese pilot of the war, and Saburo Sakai, the greatest Japanese ace to survive the conflict .