Japan has three major airports with international flights to and from the U.S.

Tokyo

Narita International Airport

• Airport code: NRT
• Tokyo's furthest airport
• 1 - 1.5 hour train into Tokyo
• $15 - $25 one-way train
  

Tokyo - Haneda International Airport

• Airport code: HND
• Tokyo's closest airport
• 30-minute train into Tokyo
• $5 - $8 one-way train
  

TIP: Whenever searching for award availability for Tokyo, use code TYO to search both Tokyo airports simultaneously.

If you had a choice between Haneda or Narita, I would fly to Haneda because it's closer to Tokyo's city center and the train ticket is cheaper.

Osaka

Kansai Osaka Airport

• Airport code: KIX
• 1-hour train into Osaka
• $6 one-way train
• Not many U.S. flights fly direct to KIX