A conflict in negotiations among multiple parties, notably MLB, the Players Association, Nippon Professional Baseball (NPB) and Shoehei Otani’s current team imperils the much anticipated arrival this winter of Japan’s best player, The Post has learned. The MLB-NPB posting agreement expired Tuesday. The sides, though, were close to an agreement to move to a system whereby the Japanese team losing a player to MLB would receive a percentage of the deal the player signed with a MLB club — believed to be between 15-20 percent. However, Otani’s team, the Nippon Ham Fighters, refused to give its needed vote to the deal unless the righty pitcher was grandfathered into the old deal, whereby the Fighters would receive the maximum $20 million in exchange for posting him prior to his Japanese free agency. The collective bargaining agreement agreed to last offseason made foreign players 25 and older who want to play in the majors unfettered free agents. Those under 25 — like the 23-year-old Otani — are subject to the international pool caps, so the righty thrower is not all that different than, say, a 16-year-old from the Dominican. Thus, he is likely to receive between $300,000 to about $3.5 million and 20 percent of that would be a pittance for the Fighters. MLB is willing to make an exception for Otani and let him come under the old system. But MLB cannot enter into any transfer agreement with any country — Japan, Korea, Cuba, Mexico, etc. — without approval from the MLB Players Association as stated in the CBA. And the union, to date, has refused to make an exception for Otani, concerned about the precedent and fairness of the player receiving, say, $300,000 and his former team $20 million.