Right-hander Naoyuki Uwasawa got the job done despite feeling “really nervous” in his Major League Baseball debut for the Boston Red Sox on Thursday. The Japanese reliever struck out one and retired all six batters in the eighth and ninth innings of Boston’s 3-1 loss to the visiting San Francisco Giants at Fenway Park. “I thought I wouldn’t be nervous, but when I stepped on the mound it was an incredible feeling,” said Uwasawa, who was recalled Thursday from Triple-A Worcester to bolster the Red Sox bullpen. The 30-year-old was posted to the majors in the offseason after nine years as a starte…