During
World War II, Hara was the
commanding officer of the
Fifth Carrier Division of the
Imperial Japanese Navy for the
Japanese attack on Pearl Harbor. His command contained the two brand-new
aircraft carriers and . During the
Battle of Coral Sea in the
South Pacific, his 5th Carrier Division successfully sank the American carrier , but
Shōkaku was heavily damaged by bombs and a large number of planes and pilots from
Zuikaku were lost. These damages put both aircraft carriers out of the war for many months, and they both missed the
Battle of Midway. Meanwhile, Hara was reassigned to command the 8th Cruiser Division, containing the large, fast
heavy cruisers and , and their escorting destroyers, during the long, bitter struggle with the Americans for the
Solomon Islands. Hara and his
warships were present for two large battles in the South Pacific: the
Battle of the Eastern Solomons and the
Battle of the Santa Cruz Islands. During the Battle of the Eastern Solomons, light carrier was detached from
Chuichi Nagumo's main carrier force and assigned to Hara's division with the task of attacking
Henderson Field on
Guadalcanal. Hara sent a strike force, consisting of six
Nakajima B5N bombers and 15
Mitsubishi A6M Zero fighters, which inflicted minor damage to the Allied airbase. Soon afterwards, USN aircraft from and found and sunk
Ryūjō. This was the last time Hara commanded a task force that included a carrier in a battle. After the large American carrier air attack on the large Japanese base at
Truk (
Operation Hailstone) in 1944, Admiral Hara was assigned to replace Admiral
Masami Kobayashi as the
commanding officer of the Japanese "
4th Fleet", though he actually commanded the land base at Truk with no
warships assigned to him. Truk was left behind by the
U.S. Navy in a rear area to "wither on the vine" in isolation, rather than being invaded and occupied. (This was the fate of many Japanese bases on Pacific islands, including the large one at
Rabaul and several on
New Guinea.) Admiral Hara was trapped at Truk without reinforcements or fresh supplies all the way through the
final surrender of Japan on September 2, 1945. Following the end of the
War in the Pacific, Hara was arrested by authorities of the U.S. Navy and then taken back to Japan to be held in the
Sugamo Prison in
Tokyo because he had been accused of
war crimes. Hara was sent to face a
military tribunal on the American island of
Guam, and there he was convicted along with other Japanese officers of "neglect of duty in connection with violations of the Laws of War committed by members of their command" for allowing the execution of U.S. Navy aircrewmen who had been captured during
air raids on Truk. Since he was the commander of the
atoll, Vice Admiral Hara was of course the highest-ranking officer from Truk to be tried for war crimes. Hara was convicted, and he was sentenced to six years in prison. He was then sent back to Sugamo Prison to serve his imprisonment. Hara's son Nobuaki graduated from the
Imperial Japanese Naval Academy just as World War II ended. When Hara was released from prison on April 19, 1951, Nobuaki took him home to a very small house in
Tokyo. Hara dedicated the remainder of his life to securing Japanese government pensions and relief for the families of Japanese, Korean, and Taiwanese servicemen imprisoned for war crimes. Hara served as a Councilor of the
Ministry of Justice (Japan) until his death at age 74 in 1964. ==Hara's sword==