Sugamo Prison- Echoes of the Yokohama Verdicts

by Dora Wan

​Towering over Tokyo, the Sunshine 60 skyscraper in Ikebukuro stands in stark contrast to Japan’s modern skyline and its complex historical legacy. The site was once home to Sugamo Prison, where the fates of many Japanese war criminals converged. Between 1945 and 1958, Sugamo Prison held most of those convicted of war crimes, including individuals tried in the Tokyo and Yokohama trials, as well as those repatriated from Allied tribunals overseas. While narratives of World War II often focus on high-profile Class A war criminals, the stories of Class B and C prisoners reveal their nuanced and often overlooked roles within Japanese society.

Sugamo: A Milieu of Its Own?
Sugamo Prison served as a key detention center for World War II war crimes suspects and convicts. Originally built by the Japanese government, the facility was taken over by the U.S. Eighth Army in October 1945 and operated until the end of the Allied Occupation in April 1952. The first detainees, including high-profile figures like Hideki Tojo, arrived in November 1945, charged with Class A “crimes against peace.” Most inmates, however, were Class B and C suspects, accused of conventional war crimes or crimes against humanity. Sugamo held approximately 2,000 prisoners, including 854 convicted in the Yokohama trials, with 51 executions carried out at the prison.
Enclosed by a 10-foot-high barbed wire fence, Sugamo appeared isolated, yet prisoners actively campaigned for public support. For instance, Class B and C prisoner Kato Tetsutaro published writings under a pseudonym, falsely claiming mistreatment by American guards and favoritism toward Class A prisoners to portray war criminals as victims of misguided leadership. In contrast, John L. Ginn, an American guard, noted in his memoir that prisoners received books, tobacco, and educational opportunities, with strict but fair conditions. Ginn stated, “The Americans had no intention of allowing the prisoners to fare better than the Japanese civilian population.” As Cold War tensions rose, U.S. personnel withdrew, and Japanese authorities resumed control by 1952, aligning with U.S. efforts to rehabilitate Japan. Most prisoners were paroled before the final releases in 1958. Despite growing public sympathy in the early 1950s, Class B and C prisoners faced social stigma and struggled to reintegrate, prompting them to pressure the Japanese government for advocacy.


Clemency Efforts
The grievances of Class B and C war criminals originated in the Yokohama trials, which prosecuted Japanese soldiers for perpetrating, ordering, or allowing atrocities, unlike Class A criminals who were tried for planning and initiating aggressive war. Debates over the legal culpability of individual soldiers led to clemency petitions seeking to reduce or overturn sentences. Partial records of 94 cases include defendants’ appeals and civilian petitions, often highlighting mitigating factors or character evidence.

Watanabe Tomikuni, confined at Sugamo Prison on February 22, 1946, and tried on August 5, 1947, was a guard at Ofuna Naval Interrogation Camp in Honshu during the war. He was convicted on three charges of mistreating American and Allied prisoners of war and sentenced to five years of hard labor. In his Defense Motion for Modification of Sentence, Watanabe’s defense presented affidavits from former prisoners to demonstrate his character. For example, Exhibits 5 and 21 stated:

“‘The Englishman’ slapped and cuffed American prisoners for minor infractions of camp rules. That ‘Englishman’ was not guilty of any serious brutality or atrocities.”

“While I was in the camp, this man [Watanabe], because of his knowledge of the English language, often served as an interpreter. He was strict while on duty but not mean or cruel. In fact, he was rather friendly off duty.”

These affidavits argued that Watanabe’s actions were shaped by his environment rather than personal intent. Ultimately, Watanabe was granted clemency, with the decision citing “the large number of affiants who have spoken very favorably of their contact with the accused.”

The case of Tomikuni Watanabe, a guard at Ofuna Naval Interrogation Camp convicted of mistreating Allied prisoners, reflects the complex attitudes in postwar Japanese society toward “ordinary” war criminals. Similarly, the case of Hirano Kenji, a medical lieutenant, illustrates the nuanced position of Class B and C war criminals. Hirano was convicted in the Yokohama trials for the murder of two B-29 airmen who were downed and captured in 1945. Stationed at Kempeitai Headquarters, Hirano was ordered to treat the airmen but instead injected them with potassium cyanide, causing their immediate deaths. Confined to Sugamo Prison in November 1947 and sentenced in 1948 to life imprisonment with hard labor, Hirano’s case drew significant public attention.

Hirano’s father, who was a well-respected doctor in Saitama Prefecture, died of apoplexy after learning of his son’s arrest. His passing prompted local communities to submit petitions for Hirano Kenji’s release as they believed that he suffered for the wrongdoing of his son and that Kenji could repay his father’s agony by continuing to serve his community as a doctor. Petitioners included 100 members of the Physicians Association of Kitasaitama-Gun, 5,619 people from Hanyu-machi in Kitasaitama-gun, 261 students from Hirano Kenji’s school, and 737 villagers who received medical services from Hirano Kenji. This active social network reflects considerable public sympathy towards war criminals, which also highlights the perplexing position of Class B and C prisoners who were perpetrators but also “ordinary” members of society.


Hirano’s defense claimed he performed a “mercy killing” to spare the airmen further torture by the Kempeitai, but this argument was rejected, as the evidence showed the killings were deliberate and unjustified. Unlike Watanabe, whose sentence was reduced due to favorable affidavits from former POWs, Hirano’s life sentence was upheld, as the court found no legal basis for euthanasia in this context. The contrasting outcomes highlight the varied success of clemency efforts, influenced by public sentiment, Cold War politics, and the specifics of each case. By 1958, most surviving Class B and C prisoners, including those from the Yokohama trials, were paroled, reflecting Japan’s push for amnesty and reintegration as part of its postwar rehabilitation. However, the social stigma faced by these individuals often persisted, complicating their return to civilian life and underscoring their dual identity as both perpetrators and community members.

Index of Hirano Kenji’s clemency documents

Petition from Naguchi Kumakiohi

Final Decision on Hirano Kenji’s Clemency Petition

Legacy of Sugamo
Sugamo Prison, demolished in the 1970s, has left little physical trace beyond a stone monument in Sunshine City’s Higashi-Ikebukuro Central Park, inscribed with “Praying for Eternal Peace,” marking the former execution site. The stories of Sugamo’s prisoners, particularly those convicted in the Yokohama trials for Class B and C war crimes, reveal the complex human dimensions of World War II. These individuals, often ordinary soldiers or low-ranking officers, were both perpetrators and products of wartime circumstances, caught between personal responsibility and societal pressures. Sugamo’s legacy underscores that while Japan’s surrender in August 1945 marked the official end of World War II, the war’s moral, legal, and social repercussions lingered in Japanese society for decades. The site’s transformation into the modern Sunshine 60 skyscraper reflects Japan’s postwar reinvention, yet the monument serves as a quiet reminder of the unresolved tensions between justice, reconciliation, and memory.

      

Works Cited
Ginn, John L. Sugamo Prison, Tokyo: An Account of the Trial and Sentencing of Japanese War Criminals in 1948, by a U.S. Participant. Jefferson, NC: McFarland & Company, 1992.
Stanford University Libraries, Virtual Tribunals. “Document 35-2232; Tomikuni Watanabe; Volume 3.” Accessed June 28, 2025. https://exhibits.stanford.edu/virtual-tribunals/catalog/dn673cg5511
Stanford University Libraries, Virtual Tribunals. “Document 35-508; Kenji Hirano; Volume 3.” Accessed June 28, 2025. https://exhibits.stanford.edu/virtual-tribunals/catalog/bj927rj2473
Stanford University Libraries, Virtual Tribunals. “Reviews of Yokohama Class B and Class C War Crimes Trials - Case Docket Number 295, Kenji Hirano.” Accessed June 28, 2025. https://exhibits.stanford.edu/virtual-tribunals/catalog/ny787np8109
Stanford University Libraries, Virtual Tribunals. “Reviews of Yokohama Class B and Class C War Crimes Trials - Case Docket Number 210, Tomikuni Watanabe.” Accessed June 28, 2025. https://exhibits.stanford.edu/virtual-tribunals/catalog/bt351md0559
Wilson, Sandra. “Prisoners in Sugamo and their Campaign for Release,1952–1953,” Japanese Studies 31, no. 2 (2011): 171-190.

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