TheCodeBreakers
Morikawa, now a captain, who, in a separate capacity, also headed the
Owada Communications Unit. The 1st Branch planned, made policy, and
distributed the results of the two operating branches. In charge was
Captain Amano, with Commander Hideo Ozawa his executive officer.
Command of the entire Tokumu Han was vested in the chief of its parent
body, the 4th Department; in effect, this gave the Tokumu Han a seat on
the Naval General Staff. In 1943 the head of the 4th Department was
Rear Admiral Gonichiro Kakimoto, and at the end of the war, Rear
Admiral Tomekichi Nomura.
In sharp distinction to American cryptanalysts, who were reading the
vast majority of Japanese messages, including those in the
cryptosystems of topmost security, the code-breakers of the Tokumu Han
failed almost completely in extracting usable information from American
messages. They did not even attempt to solve medium- and high-echelon
messages, couched in cryptosystems far beyond their ability. They
annaabi.ee 
