Tanaka missed 2 1/2 months last season while rehabilitating a partially torn ulnar collateral ligament in his right elbow. He returned for two starts in late September, and Boston chased him with an eight-run second inning in his final outing.
''It's absolutely good,'' Tanaka said through a translator. ''I think the No. 1 thing is throwing it a little bit harder than last time.''
Tanaka made 21 pitches in his initial mound session Thursday, which took place at the Yankees' minor league complex one day before reporting to spring training.
''I thought he was good,'' New York manager Joe Girardi said. ''Threw everything. Had no issues. That was encouraging.''
Tanaka is expected to have another mound session in a couple days.
Signed to a $155 million, seven-year contract in January 2014, Tanaka went 13-5 with a 2.77 ERA over 20 starts.
Tanaka's status is key to a Yankees' rotation filled with questions.
CC Sabathia threw off a bullpen mound Saturday. The 34-year-old lefty, hobbled by a degenerative cartilage problem in his right knee last season that resulted in season-ending surgery in July, made only eight starts and finished 3-4 with a career-worst 5.28 ERA.
''You're talking about a guy learning on the job, developing as time goes on,'' Girardi said. ''Worked on some different ideas with his split.''
Eovaldi started using the split-fingered fastball in his final two starts last year.
Hiroki Kuroda, who went 11-9 for the Yankees last year, opted not to return and will pitch in Japan this season.
NOTES: Girardi said the reports on Cuban infielder Yoan Moncada's private workouts for the Yankees late last week are positive. ''They're good,'' Girardi said of the 19-year old free agent. ... Orlando ''El Duque'' Hernandez arrived and joined the list of guest instructors in camp that also includes Goose Gossage and Ron Guidry.