Type 1 bomber (English: type 1 bomber [1], production number: G4M [2], allied Code: Betty [3], translation: Betty) is a G4M type naval attack aircraft manufactured by Mitsubishi company of Japan. It is the most famous Japanese bomber in the Pacific War. It is a medium-sized horizontal / torpedo dual-purpose bomber with double engines for land attack. The thick and round fuselage of the Allied code "Betty" is very like a big cigar. The early models had no armor to protect their fragile fuel tank. Therefore, it was easy to be shot down by the U.S. military and was jokingly called "flying lighter". However, with its long range and high speed, the attack aircraft became a nightmare for the allies at the beginning of the war, and served in the Japanese Navy and army throughout the war.