Masahiro Tanaka is a Japanese professional baseball player for the Tohoku Rakuten Golden Eagles of Nippon Professional Baseball (NPB). From 2007 through 2013, he played for the Eagles in NPB. Tanaka was posted by the Eagles after the 2013 season to be signed with the New York Yankees in Major League Baseball (MLB) and signed a seven-year, $155 million contract, the fifth-largest deal ever given to a pitcher at the time. He made his major league debut in 2014 and played for the Yankees through the 2020 season, before deciding to return to Japan.

The Tohoku Rakuten Golden Eagles , often shortened as the Rakuten Eagles , are a baseball team based in Sendai, Miyagi Prefecture, Japan. It has played in Nippon Professional Baseball's Pacific League since the team's formation in November 2004. The team is owned by the Internet shopping company Rakuten.