How to buy baseball tickets in Tokyo

I want to go to a Giants baseball game in September at Tokyo Dome. I already checked their schedule and they will be playing while i'm there. How do I buy tickets a game?

I just googled 'japanese baseball tickets' and saw this site. I cannot vouch for it's credibility, but if it is legitimate, it looks easy. Maybe this site, or another one could get you tickets before you come to Japan. Good luck

How stupid of of me, I forgot to link the site!

http://www.japanball.com/tickets.htm

Giants tickets are hard to get. There are many ticket brokers and although you pay more than face value, they are reputable and you can choose amongst different seats. Swallow tickets at Meiji Jingu are easy to get unless they play the Giants. Just walk right up before the game.

There are various types of tickets of Yomiuri Giants' games in Tokyo Dome.
On LAWSON Ticket website,
the cheapest (to an adult) is a ticket for standing room sold at 1,000 yen,
a ticket for a Class D seat is sold at 1,700 yen per seat,
a ticket for the highest Class S is sold at 5,900 yen per seat.

In any of the following ways, you can try your ticket without sending your personal data via Internet.
Note the 5-digit L-code in advance, which is required for ordering and buying through LAWSON.
http://l-tike.com/d1/AA02G03F1.do?DBNID=3&ALCD=1&PGCD=3...
Stopping by a shop of LAWSON convenience store, you can order your ticket via Loppi (ticket ordering machine), and pay for it at the cash desk. (A shop clerk will help you.) You will be asked of the side (1st-base side / 3rd-base side) of the seat location for a Class D / C / B / A / S seat.
Maybe your hotel's attendant will book it for you, dialing 0570-084-003 to LAWSON Ticket. This phone number is also accessible from domestic mobile phones except PHS and prepaid phones. You can buy your booked ticket at a nearby LAWSON shop.

Tickets for Giants vs. Dragons (21 - 23 Sep.) and for Giants vs. Carp (25 - 27 Sep.) will go on sale on 1 August.

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thank you so much for your answer. i will check out LAWSON while i'm in tokyo.