From Narita Airport, you can take the JR Narita Express to Tokyo Station and change to the Keihin-Tohoku Line. The journey costs ¥3300, however for just ¥200 more you can purchase a JR Suica & N'EX ticket that covers this journey and also includes a ¥2000 Suica card that can be used for train travel. Of course, this journey is fully covered if you use the Japan Rail Pass or JR East Rail Pass.
You can also use the Keisei Skyliner train from Narita, changing at Nippori for the JR Line. The Keihin-Tohoku Line stops at Nippori during the morning and evening hours. During the mid-day hours it skips Nippori, so you will have to take the Yamanote Line up to Tabata and change there to the Keihin-Tohoku Line. This is cheaper, at a cost of ¥2560. Even cheaper from Narita is to use the Keisei limited express - a commuter train which can get very crowded - and change at Nippori for the JR Line (¥1160).
Allow just over an hour to travel from Narita to Kawaguchi by Skyliner, 90 minutes by Narita Express, and 100 minutes by Keisei limited express.
From Haneda Airport, take the Tokyo Monorail to Hamamatsucho, OR the Keikyu Line to Shinagawa, and change to the JR Keihin-Tohoku Line for the run to Kawaguchi (One hour, ¥760 and ¥780, respectively)
Kawaguchi is served by several train stations at various locations in the city.
• Kawaguchi and Nishi-Kawaguchi stations are located in the southern part of the city on the JR Keihin Tohoku Line. Kawaguchi can be reached in approximately 25 minutes from Tokyo station at a cost of ¥290; Nishi-Kawaguchi is another three minutes up the line. From the western end of the Tokyo metropolis, take the Yamanote Line and change to the Keihin-Tohoku line at Tabata station, or take the Saikyo Line and change at Akabane station.
Keihin-Tohoku line trains run directly to/from Yokohama (One hour, ¥690).