Tachibana, the Rakuten president, said his team is happy to retain Tanaka if he does not reach an agreement with an MLB team.
The new posting system was negotiated after some MLB teams objected that only the richest clubs could afford to bid on top Japanese players.
Under the previous agreement, which began in 1998 and ran through last offseason, there was no cap on bidding and only the highest bidder could negotiate with the player.
Boston obtained pitcher Daisuke Matsuzaka from the Seibu Lions before the 2007 season for $51,111,111.11, and agreed to a $52 million, six-year contract. Texas got pitcher Yu Darvish from the Hokkaido Nippon Ham Fighters before the 2012 season for $51,703,411 and gave him a $56 million, six-year deal.