And the ‘sudden’ downfall of Yamamoto
https://www.thoughtco.com/operation-vengeance-death-yamamoto-2360538
The Japanese did not use the enigma. The Japanese ciphers had worse flaws. For one thing vowels could only replace vowels. The reason was because Japanese telegraph companies charged more for consonants than vowels, and enciphered messages would have contained as many vowels as consonants, rather than a bias for vowels as in natural language. Diplomatic messages were transmitted via commercial cable companies, those in and out of the U.S. via Western Union.