There are 4 international airports in Japan that can accommodate international flights.
1. Narita International Airport (near Tokyo)
2. Haneda International Airport (Tokyo)
3. Chubu Centrair International Airport (Nagoya)
4. Kansai International Airport (Osaka)
Even though the Haneda is categorized as an international airport, flags of air carriers that can use this airport are limited.
So, most international visitors whose destinations are Tokyo or other northern areas of Japan, use Narita Airport.