According to this release, Shimada has left "to focus on personal matters."
Shimada was first elected to the board in 1987. He won reelection three times before leaving in 1999 when he retired from his career as Supervisor of Operations for the Oak Grove School District, in San Jose, California.
He rejoined CalPERS in 2002 for a fourth term after winning a seat open to all CalPERS members. He was re-elected to that seat in 2006 and again in 2009.
Colleague Dale Kasler has more on Shimada's resignation here on Sacbee.com.
PHOTO: Kurato Shimada / CalPERS file