Ghosts of Honolulu by Mark Harmon and Leon Carroll, Jr. is a solid work of nonfiction subtitled A Japanese Spy, A Japanese American Spy Hunter, and the Untold Story of Pearl Harbor. It covers spy Takeo Yoshikawa and Japanese American naval intelligence agent Douglas Wada and tells an important piece of history.
Yoshikawa worked in Hawaii under the name Tadashi Morimura on behalf of Japanese intelligence, gathering information on the U.S. fleet in Pearl Harbor and how best to attack it. Wada was Nisei, born in the United States to Japanese immigrants, with their parents called Issei. Wada in his hometown of Honolulu began working for US Naval Intelligence in 1937. He was a translator for the Navy, with the scope of his work expanding through the years, especially after December 7, 1941.It was fascinating reading of how the attack on Pearl Harbor, which killed 2,403 Americans in an hour and fifteen minutes, was viewed as a failure by the Japanese military, with it having the goal of decimating U.S. Naval forces. All U.S. aircraft carriers had departed from the base, so Japanese forces focused on Battleship Row. Along with a poor hit rate by dive-bombers, the oil storage tanks and repair facilities weren't hit, enabling the port to recover fairly quickly. Ensign Kazuo Sakamaki was in a Japanese mini-submarine as part of the attack, and ran aground and was captured as the first U.S. prisoner of war of WWII. Also covered is Otto Kuehn, a former German military officer who provided signals to Japanese military about how best to attack Pearl Harbor.
The book covers the decisions that led up to people of Japanese ancestry on the West Coast of the U.S., may of them American citizens, being held in internment camps during the war. U.S. Secretary of the Navy Frank Cox made a damning, and incorrect, statement about "fifth column" work done in Hawaii contributing to the attack on Pearl Harbor. J. Edgar Hoover was one of the people speaking out against internment, but it happened anyways with President Roosevelt issuing Executive Order 9606 authorizing the military to remove anyone deemed a security threat. The Army then announced all Japanese Americans, 120,000 people, on the West Coast needed to depart "military zones" and be held in camps.
Actual investigative work done in Hawaii showed that it was members of the Japanese Consulate aiding in the attack on Pearl Harbor, not the Nisei and Issei. Those people of Japanese ancestry in Hawaii were prosecuted less than in California, explaining why there were so many more volunteers for military service from the Islands. Nisei of the U.S. 442nd and 100th fought the Germans in Northern Italy. The 442nd was created with the goal of getting three thousand volunteers from the continental US and 1,500 from Hawaii. Instead, it was more than 10,000 from Hawaii and 1,000 from the mainland.
There's also information about the U.S. bombing of Japan when Japanese spy Takeo Yoshikawa back in his homeland. Wada became the first U.S. civilian of Japanese ancestry to receive the Navy Civilian Certificate of Merit, and after the war was over, he deployed to Japan to continue working for the Navy there. He served as the only Japanese American agent in the Office of Naval Intelligence, which became NCIS, until the late 1960s. He retired from the Naval Reserve, with the rank of commander, in 1975.