Education and career
Hata was born in Yamaguchi Prefecture. He graduated from University of Tokyo in 1956, and later studied at Columbia University. During the four-year bachelor program in Tokyo, he interviewed many former Japanese army officers, including A-class criminals in the International Military Tribunal for the Far East. After graduation, he joined Ministry of Finance and later transferred to the Defense Agency, where he engaged in historiographic works of the Japanese financial and military history. His collaborative study at the Japan Association of International Relations is later published as Road to the Pacific War. Also he published some dictionaries from the University of Tokyo Press. He taught as a guest professor at Princeton University, and served as a professor at Takushoku University, Chiba University and Nihon University.
Political and academic activities
He often writes for conservative-leaning publications but distinguishes himself from other political pundits by having substantial academic publications under his name. Some of his controversial claims include a lower death toll for the Nanking massacre (at max 40,000 civilians, partly because he does not include Chinese soldiers killed in action in his estimate), and the claim that there was no organized effort by the Japanese military to forcibly recruit comfort women and that any abduction which took place was done either by renegade front line commanders (especially in South East Asia) who violated military directive or by civilian recruiters that were not part of Japanese military or government. He first came to public prominence when he outed Seiji Yoshida, who claimed to have abducted Korean women as Japanese officer, as having forged his claims. He was one of the leading participants in the historical debate over Japanese war time atrocities, which took place mainly during the 1980s and 1990s in Japan.
While admitting that some individual incidents of atrocities did indeed occur, Hata claims that there was no organized forced recruitment of comfort women by Japanese government or military, and one of his long term goals is to revise or completely retract the Kono statement.
“There were at most 20,000 comfort women. None of them were forcibly recruited (by Japanese military). Forty percent of them were from Japan, the most heavily represented nation. Many were sold to brokers by their parents. Some responded willingly to brokers’ offers; others were deceived.” I would add that, on the average, living conditions in the comfort stations were practically identical to those in brothels set up for American troops during the Vietnam War".
- “(Hata’s) handling of documents is faulty. For example, there was a document about a 1938 request from the army to (Japan’s) Home Ministry which led to the recruiting of comfort women. In (Hata’s) book, this inquiry sent from a section chief to a bureau director in the Home Ministry is disguised as instructions to various government offices. Furthermore, it allocates the number of comfort women in five prefectures, but the number of people (in Hata’s book) is nonsense. (Hata’s) numbers show 650 (comfort women) even though the document lists the total as 400. He even arbitrarily changed the wording of quotes he used.” 
- 日中戦争史 (1961)
- Reality and Illusion; the Hidden Crisis between Japan and the U.S.S.R., 1932-1934 (1967)
- 官僚の研究 不滅のパワー 1868-1983(1983)
- Japanese Naval Aces and Fighter Units in World War II (1989)
- Hirohito: the Showa Emperor in War and Peace (2007)
- Takashi Yoshida, The Making of the "Rape of Nanking" (New York: Oxford University Press, 2006), 98-100.
- Sanger, David E. (1992-08-08). "Japanese Veteran Presses Wartime-Brothel Issue". New York Times. Retrieved 2012-08-19.
- Ikuhiko Hata. "No Organized or Forced Recruitment: Misconceptions about Comfort Women and the Japanese Military" (pdf). Retrieved 2007-11-10. "For the long term, we will need to retract or revise the Kono statement"
- "Criticism of Ikuhiko Hata’s 'Comfort Women and Sex in War'". Friday Weekly, #290, Nov. 5th, 1999 (in Japanese). Hayashi Hirofumi. Retrieved 2013-05-28. "資料の扱いもずさんさである。たとえば、一九三八年に内務省が陸軍からの依頼をうけて慰安婦の徴集の便宜を図った資料がある。この本では内務省警保局の課長が局長に出した伺い書が、内務省から各地方庁への「指示」に化けている。さらに五府県に慰安婦の数を割当てているが、その人数がでたらめで、資料では合計が四〇〇人になるのに、氏の数字では六五〇人とされてしまっている。引用も言葉を勝手に変えた..."
- WorldCat Identities: Hata, Ikuhiko 1932-
- Road to the Pacific War, 1-7. Tokyo: Japan Association of International Relations, Asahi Shinbun, 1963
- University Tokyo Press (Japanese)