Tokyo Dome

Tokyo Dome is mecca for sports. There is not only baseball game, but also pro wrestling, american football, K-1 or concert.
Also There was WBC and MLB opening series at Tokyo dome.

Home Team
Tokyo Yomiuri Giants

Access
There are a multitude of options to get to stadium.
If you take JR, get off Suidobashi station.
If you take Tokyo metro subway, get off Korakuen station.
Railway map is here.
https://www.jreast.co.jp/e/routemaps/pdf/routemap_majorrailsub.pdf

Demand for ticket
★★★☆☆
Right field bleacher is for Tokyo Giants fans. It'll be sold out every game.
However stadium is large. You may get tickets on game day, except rivalry match.

Ticket Prices
Expensive
Infield reserved: 6,100JPY
Outfield reserved: 2,300JPY
Bleacher: 2,200JPY

Must to do
To go Japan baseball HOF.
Tokyo Dome have Japan baseball HOF. Visit HOF and see old player's bat and glove!
Admission fee is 600JPY (Adult)

Must have
Actually, Tokyo dome don't have speciality food. Also, Price is expensive.
I suggest you have or buy something out of the stadium.
If I must say, I recommend DML sand. It's similar to Tokyo Dome in shape.