# Ocean Island massacre

The Ocean Island massacre occurred on 20 August 1945 when between 150 and 200 civilians were killed in a mass execution by members of a Japanese naval garrison unit. The civilians, all originally inhabitants from other parts of the Gilbert Islands, had been brought to Ocean Island as slave labour. Perpetrated five days after the official Japanese announcement of surrender at the end of the Second World War, the nature of the massacre was only revealed four months later due to the emergence of a sole survivor, Kabunare Koura of Nikunau, who had remained in hiding until December 1945. Initially, the commander of the unit, Suzuki Naoomi, claimed that the civilian population had been killed during a rebellion, but the revelation of Kabunare's testimony and subsequent confessions from lower ranking participants led to war crimes prosecutions by the Australian military. In total, 21 Imperial Japanese Navy (IJN) personnel were convicted, of whom eight, including Naoomi, were executed, for their roles in the mass atrocity.

## War crimes trials

IJN personnel convicted of war crimes on Ocean Island and sentenced to death :
| Name | Name (Kanji) | Rank | Sentence at trial | Confirmed sentence |
| Miyasaka Denji | 宮坂傳治 | Lieutenant | Death by hanging | Executed on 13 August 1946 |
| Nara Yoshio | 奈良賀男 | Lieutenant | Death by hanging | 20 years imprisonment$^‡$ |
| Ōtomo Torizō | 大友酉蔵 | Sub-lieutenant | Death by hanging | Executed on 10 August 1946 |
| Sakamoto Chūjirō | 坂本忠次郎 | Sub-lieutenant | Death by hanging | Executed on 10 August 1946 |
| Sakata Jirō | 坂田二郎 | Lieutenant | Death by hanging | Executed on 15 August 1946 |
| Sakuma Wataru | 佐久間彌 | Lieutenant | Death by hanging | Executed on 10 August 1946 |
| Suzuki Naoomi | 鈴木直臣 | Lieutenant-commander | Death by hanging | Executed on 7 July 1947* |
| Yajima Eiichi | 矢嶋榮一 | Lieutenant | Death by hanging | Executed on 10 August 1946 |
| Yamaguchi Nobuaki | 山口？(健)章 | Lieutenant | Death by hanging | Executed on 12 October 1946 |
$^‡$ On the recommendation of the Judge Advocate General, death sentence was commuted to a prison term of 20 years.
* Lieutenant-commander Suzuki's execution was delayed due to appearing as a witness in the trial of Major General Hirota Akira.
IJN personnel convicted of war crimes on Ocean Island and sentenced to imprisonment :
| Name | Name (Kanji) | Rank | Sentence at trial | Confirmed sentence |
| Arai Kakuzō | 荒井角蔵 | Chief petty officer | 7 years imprisonment | 7 years imprisonment |
| Hanawa Eiji | 塙栄次 | Sub-lieutenant | 20 years imprisonment | 20 years imprisonment |
| Hiraki Sakae | 平木榮 | Sub-lieutenant | 20 years imprisonment | 20 years imprisonment |
| Iijima Tadashi | 飯島重 | Ensign | 20 years imprisonment | 20 years imprisonment |
| Ishii Sadazō | 石井定臓 | Sub-lieutenant | 20 years imprisonment | 20 years imprisonment |
| Kiyohara Naoyoshi | 清原直美 | Sub-lieutenant | 20 years imprisonment | 20 years imprisonment |
| Konno Hiroshi | 今野浩 | Warrant officer | 7 years imprisonment | 7 years imprisonment |
| Shinozawa Yoshiharu | 篠澤美春 | Ensign | 15 years imprisonment | 15 years imprisonment |
| Sugino Tsuchinosuke | 杉野土之助 | Ensign | 15 years imprisonment | 15 years imprisonment |
| Tsuchiike Masatarō | 土池政太郎 | Sub-lieutenant | 20 years imprisonment | 20 years imprisonment |
| Yasuda Harumi | 安田春美 | Ensign | 15 years imprisonment | 15 years imprisonment |
| Yoshida Itsuo | 吉田逸雄 | Sub-lieutenant | 20 years imprisonment | 20 years imprisonment |
IJN personnel acquitted of war crimes on Ocean Island :
| Name | Name (Kanji) | Rank | Ref. |
| Ono Kaneichi | 小野兼一 | Chief petty officer | |
| Yachi Sumio | 谷地澄雄 | Ensign | |