He was born on May 03, 1904 and graduated from the Department of Electrical Engineering at Tokyo University in the year 1928. Joined Tokyo Electric Co., Ltd, which in turn merged with Shibaura Engineering Works Co., Ltd., in 1939 into Tokyo Shibaura Electric Co., Ltd., now known as Toshiba Corporation. He was engaged in the research on radio communications related technologies including traveling wave tube radar for which he lately won the Okouchi Memorial Technology Award.

In the year 1948, after the World War II, when he was working as a deputy senior manager of the Research Department of Mazda Research Laboratories in Toshiba, he had the opportunity of understanding the technologies of electronic computers in U.S and Europe. Visioning the future growth, he chose electronic computer as his research theme. Due to non-availability of related information on electronic computers at that time, he went to the library of GHQ (General Head Quarters) of the Occupation Army, located in Hibiya. In addition, he requested Professor Yamashita Hideo of the University of Tokyo to support and guide his research. With all his effort after presenting mimeographed copies of his research results to the people in the company, to the faculty of engineering and science of University of Tokyo, the laboratory decided in November, 1950 to start a research team for computers. The team consisted of three researchers, namely Mita, Matsukuma, and Yagi, and started researching on EDVAC. Toshiba considered the research carried out by this team as an applied activity for vacuum tubes, which was then a major business area. During the research, the team encountered numerous problems that were never experienced before. This as a blessing in disguise, showed them the ways and means to resolve those issues. To share a few, a) the issue of increased number of vacuum tubes and the durability of the vacuum tube showed the team to develop a tube with long life, b). they, after recognizing the significance of random access capability feature of memory, based on the idea of Williams of University of Manchester, developed Williams Tube.

In 1951, the Grants-in-Aid for Scientific Research by the Ministry of Education enabled the University of Tokyo to initiate the project "Research of Electronic Computers", lead by Professor Yamashita. Keeping in mind Toshiba’s remarkable achievements on the research of Electronic Computers, Toshiba was invited to take part in the Tokyo University. As a result, University of Tokyo and Toshiba have started the TAC project collaboratively sharing hardware and software responsibilities. Toshiba, however in 1956 withdrew from TAC project. Later the University of Tokyo took full control of the TAC project and successfully completed in 1959.

Mita devoted all of his energy for the research without showing any interest in formal degrees, titles or any other secular status. He never even talked much but occasionally used to show some wit and humor in his conversations and used to smile winsomely.

• Prize of Progress for "Research and Development of a Electronic Computer"
  (1955, The Institute of Electrical Engineers of Japan)
• The 13th Okouchi Memorial Technology Award
  for "Utilization of a traveling-wave tube radar system"(1966)