UPDATE - The A's have reached a minor league agreement with Okajima, pending physical, according to Ken Rosenthal of FOX Sports.
Okajima spent the 2012 season with the Softbank Hawks of the Japan Pacific League, maintaining an ERA of 0.94 with a strikeout-to-walk ratio of 6.0. The Hawks released the left-hander from his contract recently so that he could pursue an opportunity to sign with a major league club.
Okajima signed with the Boston Red Sox prior to the 2007 season and was an effective reliever for them over the next three seasons. From 2007-09, the left-hander maintained a 2.72 ERA with a 2.89 strikeout-to-walk ratio. However, from 2010-11 Okajima struggled to the tune of a 4.47 ERA and 1.56 strikeout-to-walk ratio.
Following the Jed Lowrie trade with the Houston Astros, A's general manager Billy Beane said he was finished making significant moves this offseason. However, Beane admitted that he could make other minor additions.