One of the best kept secrets in the world of Japanese trains, the 青春18きっぷ Seishun jûhachi kippu, or Seishun 18 Ticket, gives you five unlimited one-day passes on the JR network for ¥11,500. That means you can go anywhere in the entire stinking country for less than $30 one-way, as long as you finish your travel within a day. You can buy it at any Green Window in any JR station.

"So what's the catch?" Well, there are a few. First of all, it's only sold during vacation periods in the spring, summer, and winter (its name literally means "youth ticket," but anybody of any age is allowed to use it), and you can't use the ticket outside of the season you buy it. That said, you can't use a Seishun 18 ticket on the Shinkansen, or on any other limited express train. You also can't use it on sleeper trains, or for first-class seats. You can use it on rapid service trains that require reservations, but you have to purchase a reservation separately. All other rapid service and local trains are fair game. The other main catch is that a "day," in this definition, is a period between 12:00 AM and 11:59 PM. So if you get on a train at 11 PM and get off at 1 AM, you've used up two days' worth of tickets.

Now here are some bonuses. First of all, if you're travelling with four of your friends, you can all split a single Seishun 18 at the same time. Or you can travel with one friend for a day, and two friends for another day, or whatever. There are no restrictions on how many people can use the ticket, as long as it is only used for five man-days of travel. And once you start traveling on a fifth of a ticket, you can use that fifth to get on and off as many times as you want to until midnight (if you want to get food, do some sightseeing, etc).

The most popular use for the Seishun 18 is the Moonlight Nagara train, an overnight rapid service train which leaves Tokyo Station at 11:43 PM and arrives in Ogaki (about an hour away from Kyoto) at 6:55 AM, stopping in Odawara and Nagoya along the way. Seishunology majors board the train at Yokohama at 12:10 AM, then ride to Ogaki and transfer to a regular daytime train for the rest of their westward journey. When going east toward Tokyo, the date changes at Anjo, about 30 minutes east of Nagoya, so the journey will use two Seishun 18's.

A slightly easier, if slower, way to get around Japan with the Seishun 18 is to travel during the day. Here are some rough travel times, in hours, for regular train trips starting in Tokyo:

Kofu - 2.5 (Chuo line)
Nagano - 6 (Chuo line)
Nagoya - 6 (Tokaido line)
Sendai - 6.5 (Tohoku line)
Kyoto - 8.5 (Tokaido line)
Osaka - 9 (Tokaido line)
Morioka - 11 (Tohoku line)
Okayama - 12 (Tokaido and Sanyo lines)
Hiroshima - 15 (Tokaido and Sanyo lines)
Aomori - 16 (Tohoku line)
Fukuoka - 20 (Tokaido and Sanyo lines)

You'll have to connect several times, and budget your time while keeping in mind that most lines are only in operation from 5 AM to midnight. Going to Hokkaido or Kyushu from Tokyo in one day is pretty much out of the question: you'll have to buckle down and buy an airplane or Shinkansen ticket. (and don't even ASK about Okinawa)

For more information on the Seishun 18 and its use, visit (Engrish) or (Japanese).