Although he had no knowledge of a planned attack on Naval Station Pearl Harbor, Yoshikawa assumed that the intelligence would help prepare for such an eventuality and worked tirelessly to that end. His reports were transmitted by the Japanese consulate in PURPLE code to the Foreign Ministry, which passed them on to the Navy. Although the code had been broken by Allied codebreakers and messages to and from Tokyo were intercepted and decrypted, communications between Tokyo and the consulate were considered low-priority because they contained so many messages that were entirely commercial in nature. However, one such message addressed to Kita (but actually to Yoshikawa) and sent on September 24, 1941, should have received more attention. It divided Pearl Harbor into five distinct zones and requested that the location and number of warships be indicated on a "plot" (i.e., grid) of the harbor. However, due to delays caused by staff shortages and other priorities the message was not decrypted and distributed until mid-October, and then dismissed as being of little consequence. However, it was the reports that he sent twice a week based on this request that enabled Admiral Isoroku Yamamoto to finalize his plan for the attack.