Martin was released by the Red Sox on Wednesday in order to pursue opportunities in Japan, Jason Mastrodonato of the Boston Herald reports.
The 27-year-old made his first two major-league appearances last year for the Red Sox, allowing a run in 2.1 innings. He's spent the entirety of the 2018 season with Triple-A Pawtucket, posting a 3.33 ERA in 51.1 innings of relief.