Kazuo Hirai spent his youth outside Japan and attended schools overseas as well as ASIJ(American School in Japan). In September 1979 he entered what was then the Division of Social Sciences at ICU's College of Liberal Arts. He studied Japanese in the Japanese Language Programs required for all September entrants while also taking a number of courses in international law with Professor Toshiki Mogami (now an emeritus professor of ICU). With classes piquing his interest in the subject, he joined a group studying of international law with friends and classmates with a strong desire to "work at the UN one day" He received his bachelor's degree in March 1984.
After graduation he joined CBS/Sony Records (now Sony Music Entertainment(Japan)Inc.). In August 1995 he transferred to Sony Computer Entertainment America where he greatly expanded development of the company's PlayStation product in North America. At SCEA he went on to become one of its EVP (Executive Vice President) and COO (Chief Operating Officer) in July 1996, President and COO in April 1999, and President and CEO in August 2003.
In December 2006 Hirai was appointed to Sony Computer Entertainment Inc. as its President and group COO, later becoming President and Group CEO in June 2007. At Sony Corporation he served as EVP from April 2009 and as Representative Corporate Executive Officer, Executive Deputy President from April 2011. He became Chairman of SCEI in September 2011, Representative Corporate Executive Officer, President and CEO of Sony Corporation in April 2012, and Member of the Board in June 2012.