Kawaguchi (川口) is a city in Saitama prefecture.
The first stop into Saitama prefecture travelling north from Tokyo on the JR Keihin-Tohoku line. As Kawaguchi lies over the Arakawa (River Ara) and outside the boundaries of Tokyo city it was the site of much industrial development before, and especially after, the Second World War. A great many smelting and die-casting foundries were set up and the city gained a reputation for small scale steel and precision instrument production (it was apparently the place in Japan for the production of athletic shot-puts).
However as the urban sprawl spread across the Kanto plain the need for living space grew so in the last five years most of the factories and plants in Kawaguchi have been demolished to make way for apartment blocks and high rise condominiums. The station area has been extensively redeveloped with a great many new shops and shopping centers opening up. These two developments have changed the face of Kawaguchi from an aging and declining industrial town into a thriving commuter town with an expanding number of young families.
Its location means that it's great for getting into central Tokyo (Tokyo station 23 minutes, Shinjuku 21 minutes, Ebisu 28 minutes, Roppongi 41 minutes) but because it's in Saitama the rents and costs are proportionally lower.
Lastly as Kawaguchi is on the River Ara ("Kawaguchi" means river mouth) it means that unlike many towns there is a lot of greenery to be found. Along the river bank, between the river and the raised flood banks, the city government has put football (soccer), rugby and baseball pitches, a couple of golf course, picnic areas and just open space for all to use. It makes a big difference to have somewhere green and quiet to head after a week working in the concrete jungle.
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.
Keihin-Tohoku line trains run directly to/from Yokohama (One hour, ¥690).
From Shinjuku station, walk out the West exit. Go to the ground floor of Yasuda Seimei 2 to take"Keio Bus" for 1700 yen. The trip takes 1 hr. 45 min.
JGH Tokyo Hostel is a great, cheap place to stay. It's a short walk from Nishi-Kawaguchi Station, the second stop outside Tokyo-proper, and from there a short trip into Tokyo. They claim to be the cheapest accomodation in Tokyo and it's a believable claim. The manager/receptionist speaks good English and is very friendly. There's a supermarket just 100 m down the road, open till midnight, and a 24 hour coin laundromat opposite. Single capsule style rooms from ¥1495, Single private for ¥2610, Double for ¥1675 per person (all shared bathroom). Bookings can be made through Hostel World .