"[T]hose men of influence and character who might have assisted me in my secret mission were unanimously uncooperative..." 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 American 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. When he heard the "East wind, rain" code phrase on the short wave radio bringing the news from Tokyo signaling an attack against America, Yoshikawa destroyed all evidence of his activities. When the FBI picked him up on the day of the attack, there was no incriminating evidence of his espionage. He eventually returned to Japan in August 1942 in a diplomat prisoner exchange. It was not known for some time that he was the chief Japanese agent in Hawaii. Yoshikawa continued to work for naval intelligence during the remainder of the war. When the war ended and Japan was occupied by U.S. forces, he went into hiding (disguised as a Buddhist monk) for fear of being prosecuted for his role in the Pearl Harbor attack. He returned to his wife (whom he married shortly after his return from the U.S.) when the occupation ended. Yoshikawa never received official recognition of his services during the war. In 1955, he opened a candy business but it failed as word spread of his role in the war. The locals blamed Yoshikawa for the war. "They even blamed me for the atomic bomb," he declared in one interview. Penniless and jobless, he was supported by his wife for the rest of his life via her position selling insurance.