The NPB is thinking about suspending the season during the 2020 Tokyo Olympics. The media learned on September 11 that the season could be suspended for twenty-three days, between July 22 and August 13. The proposal could be finalized during an owner meeting on September 12.
The NPB is planning to schedule the 2020 All-Star series on July 19 and 20, with an alternate date on July 21. This will mean the season will start about a week earlier than usual (possibly March 20). The end of the Nippon Series could be pushed back from ten days to two weeks (mid-November).
[UPDATE 9/12 @ 2:26pm]
Jingu Stadium, Yokohama Stadium, and Sapporo Dome will not be available during the Olympics.
[UPDATE 9/13 @ 3:42am]
The 2020 season will be suspended between July 22 and August 13. The season is slated to begin on March 20, Inter-league play on May 26, the Climax Series on October 24, and the Nippon Series on November 7.
Source: Daily Sports 9/12/2018
[UPDATE 9/14 @ 2:48am]
The earlier start and the annual Spring Koshien Tournament will mean the Hanshin Tigers will not be able to use any of the Koshien Stadium facilities for a longer period of time.
Source: Daily Sports 9/13/2018