Naohiko Kitsuta, a managing director at Kohlberg Kravis Roberts, resigned last month.
A spokeswoman for the firm declined to comment as to the reason for the departure or what Kitsuta plans to do next.
Based in Tokyo, Kitsuta joined KKR in February 2007 from Japanese buyout firm MKS Partners, where he was responsible for buyouts in the consumer services and retail sectors.
KKR set up its Japan operations in 2005 and there are presently nine investment professionals in its Tokyo office.
In September 2008, KKR appointed Yoshiharu Fukuhara, honorary chairman of luxury cosmetic line Shiseido, as a senior advisor for its activities in the country.
In 2007, the firm took a JPY20 billion ($222 million) stake in credit cart firm Orient, which was being bailed out by a Mizuho Financial Group-led consortium at the time.
Foreign private equity firms have found it difficult to cut deals in the country where many businesses eye the private equity industry with suspicion.