The following briefly describes his successful career as a historian scholar. The information is available on the net in Japanese and is not translated here.
Japan: The important Historian Dr. Hata speaks on World War II issues (English subtitles)
Great that this has English subtitles. Normally only in Japanese, which is like locking it in a vault:
"Professor HATA Ikuhiko graduated from the University of Tokyo in 1956 and received his PhD from the same institution in 1974. He worked as chief historian of the Japanese Ministry of Finance between 1956 and 1976 and during this period from 1963 to 1965 he was also a research assistant at Harvard University. After resigning his post at the Finance Ministry Hata served as a visiting professor at Princeton University from 1977 to 1978 and then was a history professor at Takushoku University from 1980 to 1993, at Chiba University from 1994 to 1997, and at Nihon University from 1997 to 2002
"Hata's scholarship has been widely praised. Historian Edward Drea, for instance, has written that Hata's "published works are models of scholarship, research, accuracy, and judicious interpretation", and Joshua A. Fogel, a historian of China at York University, concurs that Hata "is an eminent scholar who has for over forty years been writing numerous excellent studies of Japan at war.""