The infield dirt area at Koshien Stadium will be expanded. About two meters of outfield grass will be removed. The Hanshin Tigers are hoping the larger infield will lead to fewer injuries and a better fielding surface for infielders.
The infield was also increased by around a meter in January 2016. After the current changes, the radius of the infield from the rubber will be 33.5 meters. Modifications will take about a week. Work will begin on June 5, when the team heads off for a six-game road trip.
Source: Sponichi 5/30/2017
[UPDATE 6/5 @ 10:44pm]
Work to expand the infield dirt further into the outfield began today. The modified field will first be used by the Ni-gun team on June 9 against Softbank.
[UPDATE 6/6 @ 7:46pm]
The media learned on June 5 that the bullpen areas in foul territory are being removed for the safety of players. The bullpens were once removed in 2007, but brought back in 2013 for the fans. The bullpens are expected to return during high school tournaments.
Source: Daily Sports 6/6/2017