Late in the evening of December 6, 1941, Yoshikawa sat at his desk in Honolulu’s Japanese Consulate. The vice consul prepared to send out his final message to Tokyo. Looking younger than his 27 years, Tadashi Morimura—his name since he landed nearly nine months prior—thought about how to boil down what he had seen that day. In his mind’s eye, he could instantly bring the Pearl Harbor basin, seven miles off, into view. He saw the 39 United States warships, the heart of the Pacific Fleet, moored around the basin—including the nine hulking gray battleships lashed in a double line on Battleship Row off Ford Island. The hangars and patrol planes of the Ford Island Naval Air Station spread across the center of the basin. He pictured the Navy Yard’s dry docks, sub berths, massive supply house and oil tank farms. Inland, he envisioned the Army’s Schofield Barracks and Hickham and Wheeler Air Fields, where long double lines of fighter planes with their wings folded up like damselflies at rest sat parked down the center of the runways.

Morimura considered his words carefully. They might be his last. He could not know precisely when Japan would attack, but years of preparation as a naval intelligence operative told him it would not be long now....