The Fukuoka Softbank Hawks and Tokyo Yakult Swallows have already proven themselves to be the top teams in the Pacific and Central Leagues.
The next week will decide which club can call itself the best of the best in 2015.
The champions of NPB's two leagues took turns working out at Yafuoku Dome on Friday afternoon as they put the finishing touches on their preparation for this year's Japan Series, which begins on Saturday. Game 1 is scheduled to begin at 6:30 p.m., with Rugby World Cup star Ayumu Goromaru scheduled to throw out the ceremonial first pitch.