Sponichi has a brief primer article on Inter-league play for those that need a refresher. I've translated it below:
- Inter-league play takes place between 5/12 - 6/13. Every team will play four games (two home / two road) against the six teams not in their league.
- The Inter-league champion will be the team that finishes with the best record. In cases where there are two teams with the same record, two factors can decide which teams becomes champion: 1) direct vs information for the current season, and / or 2) standing information from 2009.
- The Inter-league champion team will be awarded 50M yen. One player from the champion team will be selected as the MVP and will be awarded 2M yen. There is also a Nissay Award as well (selected from any of the 12 NPB teams).
- Other rules:
- There are no suspended games
- Teams do not have to make advanced announcements of their starters
- The DH-rule will only be used in Pacific League stadiums
- There can only be 1 manager, 8 coaches, 25 players, one マネジャー (helps oversee various tasks), one trainer, one interpreter (or two if there is a need for two languages other than Japanese), one scorer (advanced scout), and one public relations official.