The Japan Baseball Regulations Committee announced today that they made a number of changes to the rulebook (effective beginning on 2/15). Of note:
Rule 1.10a: The diameter of wooden bats can be no bigger than 6.6 cm (instead of 7 cm).
Rule 1.16a: Runners are required to wear helmets.
Rule 1.16e: Base coaches in the coaches boxes are required to wear helmets.
Rules 5.10f Note, 6.05a Notes, 7.04c Notes: These notes were all deleted, meaning players can now catch a ball in foul territory and step into the dugout without the ball becoming dead and runners getting awarded a base.
Rule 8.02a1: Pitchers can touch their mouths or lips with their throwing hand even if they are on the mound, provided they wipe their hand clean before standing on the rubber.
To see all the changes (in Japanese), click here.