Details of the agreement weren't immediately released.
Tanaka's professional baseball career began in Japan with the Golden Eagles in 2007. He won the Sawamura Award as the best pitcher in Nippon Professional Baseball in 2011 and 2013.
After the NPB posted him for all 30 Major League Baseball teams to bid on, Tanaka joined the Yankees in January 2014. The right-hander signed a seven-year, $155 million contract, the largest deal ever given to a Japanese player.
Despite some durability issues in New York, Tanaka proved well worth the investment. He was named to the AL All-Star team twice (2014, 2019) and posted a 3.74 ERA with 991 strikeouts and 983 hits allowed in 1,054.1 innings.
Tanaka had problems staying on the field at times. The 32-year-old never reached 200 innings in a season and only made 30 starts three times in seven years with the Yankees.
When Tanaka was throwing his best, though, few pitchers in MLB were better. He has a 3.33 ERA in 10 career playoff appearances.
The Golden Eagles are likely betting on Tanaka as a key cog in their starting rotation. His track record of success in New York is a strong indication that his transition back to Japan won't be difficult.