The Giants announced on Wednesday that they've struck a deal with McDonald's Japan that will allow fans to purchase a Big Mac, medium fries, chicken nuggets (5-piece), and a medium drink for 650 yen. There are a couple of catches though: the offer is good only for non-Inter-league games played at Tokyo Dome (51 possible games); both teams will need to hit home runs; the offer will be good for up to one day after the game; and you will need to ask for the Home Run Set when you place your order.
In addition to this, fans that have ticket stubs (valued at or over 1,700 yen) to the actual game in question, can get the Home Run Set for free. What's more, even if both teams don't hit home runs, fans can turn in their ticket stubs for a free Big Mac (again, only to home games at Tokyo Dome).
McDonald's is also running a contest where school kids (and their parents / guardians) can win tickets to Giants' games. First prize also includes a tour of Tokyo Dome and what I'm guessing is a chance to throw out a ceremonial first pitch.