Let's start in Tokyo. Here is the workhorse, the lifeblood of the city, the JR Yamanote Line, at Ikebukuro Station. Three-and-a-half million people ride the Yamanote Line every day. Which makes sense, as it makes a loop around central Tokyo -- as a matter of fact, it defines "central" Tokyo; when people say that, they're generally referring to the 25 square miles within the Yamanote loop -- and it connects to every other line in the city. At rush hour, a train comes every two-and-a-half minutes, and during morning rush, seats are folded up to make every car standing-room only. Every train is 11 cars long, some cars have six doors, and every train fills to overflowing. On my first morning in Tokyo, I decided to try out the Yamanote Line during rush hour, to experience Tokyo as the locals do, riding to work every day. You've heard the stories about staff pushing people onto trains so doors can close? They're true. By the way, with the exception of a few short tunnels, the Yamanote Line is either elevated or in a trench, so unlike an underground train, it allows you to see your surroundings -- making it a great way to tour central Tokyo.

Platform at Ikebukuro Station.

Ikebukuro Station. Here you get a sense of the station's size -- and bear in mind that while only Shinjuku Station is busier (Ikeukuro is a major transfer point for commuters from the northwestern suburbs), Tokyo Station is larger in terms of platforms, with a total of 20. Ikebukuro is flanked by two of the world's largest department stores, Tobu and Seibu. The Japanese department store is a world away from its American counterpart -- it's much larger, more crowded, and altogether more overwhelming than the one at your local mall ... of course. Also, note the smokestack in back. In Japan, my friend Aaron told me, there is "no zoning." He may have been exaggerating, but there are waste incinerators in residential neighborhoods; nor does there seem to be much regulation of emissions, judging from the smoke -- the pollution, it would appear -- pouring forth from power plants and factories.

Shinjuku Station. As with all else in Japan, it's difficult to describe the scale of Shinjuku Station, and this photo of a mere fraction of the mass of humanity inside at any given moment doesn't do it justice. It does, however, give some idea of the sort of signage that can be found throughout the Tokyo rail network. Without it, I shudder to think how hard it would be to find one's way.

Departure board at Shinjuku Station.

Platform at Shinjuku Station. As Shinjuku is Tokyo's "new downtown," featuring its largest financial and entertainment districts, Shinjuku Station is a major transfer point, serving 11 lines and connected by pedestrian tunnel to not one, two or three, but four underground stations. By the way, note the curving platform -- something virtually unheard of in America.

Now for a change of pace: Tokyo's last surviving streetcar route, the Toden Arakawa Line. You know you're seriously geeky about trains when on your first morning in Tokyo, you ... ride a tram. But the end of the line was near my hotel, and like the Yamanote Line, it's a fine way to explore Tokyo neighborhoods; only these neighborhoods, on the city's north side, are off of the usual tourist track. Like the streetcar, they're slower. For the most part, the line follows its own right-of-way, a railroad rambling its way past homes and shops, crossing streets the old-fashioned way (old-fashioned in Japan, at least). It also serves several schools, if the hordes of schoolgirls on my car were any indication.

Toden Arakawa Line, near Otsuka Station.

Before we depart Tokyo, more hardcore nerdiness: The railyard at Minami-senju Station, near my hotel in northeastern Tokyo. It's hardly the largest in the city, but then that should tell you something.

And now the world's greatest train, Shinkansen, approaching Tokyo Station. Of course Japanese bullet trains are fast -- scary fast. But they're also gigantic: The largest are a quarter-mile long, with 1,200 seats. Including standing room-only passengers, a fully-loaded Shinkansen (translation: "New Trunk Line") can carry three times as many people as a 747. And there are nearly 280 daily trains along the Tokaido Line between Tokyo and Osaka, more than the total number of planes between all Bay Area and greater L.A. airports -- and that is the world's busiest air corridor. Not that Shinkansen are really comparable to planes; they may be roughly as fast when you factor in airport security, waiting times to check-in and board, and travel to outlying fields (Shinkansen stations are located in city centers, connected to local transit networks), but they're roomier and smoother, more comfortable. And safer -- in 42 years, Shinkansen has had exactly one accident, caused by an earthquake, and not a single person was killed. (In other words, if you're a California voter, please click here.) By the way, you can find 30-second clips shot from Shinkansen in the Video section.

700 and 300 series Shinkansen, at Tokyo Station. The 700, with its distinctive "duck bill" of a nose, seemed to me to be the most commonly used model on the Tokyo-Osaka mainline.

Another 700 series Shinkansen, at Shin-osaka Station, this time bearing the Hikari Rail Star branding.

100 series Shinkansen, at Hiroshima Station. This is the oldest model I saw, dating to the mid-'80s; unfortunately, I didn't get to see any 200 series (don't ask why the "200" designation predated "100") or the original, truly bullet-nosed 0 series. Nor did I get to see the hypersleek, megafuturistic 500 series (which, strangely, predates model 700). For everything you ever wanted to know about Shinkansen models and more, by the way, click here.

Shinkansen, approaching Kyoto Station.

Shinkansen, approaching Nagoya Station. Here you see just how long a full-length Shinkansen can be (and just how bad the air quality can get in a Japanese city; yes, it's haze and smog).

Shinkansen departure board, at Nagoya Station. Again you can see just how clear and consistent Japanese signage is -- and how easy it is on English-speaking travelers.

Shinkansen, at Nagoya Station. It's my dream job. But seriously, what a rush. Shinkansen are so long that by the time the last car leaves a station, they've already worked up a head of steam. For that matter, they're still booking as they enter a station ... it can be a bit unnerving out on the platform. Although I will say this: The most enjoyable meal I had in Japan was in a standup noodle joint (the kind where you press a button next to a photo of your order, deposit your yen, and hand the ticket to an attendant), on a platform, as Shinkansen sped past just steps away.

Now we move on to the Linimo Line, Nagoya. Looks like an ordinary people mover, right? Like the kind you see at airports in the States, with rubber tires on a concrete guideway? Wrong -- see any wheels?

It's a maglev -- powered by magnetic levitation -- one of just two in service in the entire world (the other is in Shanghai). So did I get to go several hundred miles an hour? Sadly, no. The Linimo Line stops every half-mile or so, topping out at around 60 mph. So why waste the most expensive, next-generation transit technology possible on a short route in the distant suburbs? Like the Seattle Monorail, it was built for a world's fair. Whatever-- at least I can now say that I've been on a maglev. It cost 720 yen (~$6.50) to make an 11-mile round trip, and I had to spend an hour on the subway, on my last morning in Japan, hauling luggage, just to get there ... but it was well worth it.

Next up: Two versions (I also saw, but didn't photograph, a newer vehicle) of the Hiroshima Streetcar, at Hiroshima Station. Hiroshima's oldest trams were donated to it by other Japanese cities after the war. Peace Memorial Park (see the Nagoya, Kyoto, Osaka + Hiroshima section) is just a 15-minute ride on the #2 line from the Shinkansen station.

Now for some standard JR signage, at Owari-ichinomiya Station, Ichinomiya. Wherever you go in Japan, from the island of Hokkaido off the coast of Russia to subtropical Kyushu more than a thousand miles south, you will find the exact same style of sign at every Japan Rail station -- not just on platforms, but directing you to exits, restrooms and connecting transit, all in English as well as Japanese. This one happens to be along the JR Tokaido Line (not to be confused with the Shinkansen line of the same name) in a suburb of Nagoya. Someone really ought to put together a series of photos of JR signs for station names, something collectible perhaps ... cough! Aaron?

Unfortunately, this sign of the times is also a common sight. In Japan, chikan -- gropers -- have become such a problem that at rush hour, whole cars are set aside for women. I spied this example at Umeda Station, Osaka.

For the record: In Tokyo, I also rode the Yurikamome New Transit Line, a people mover, along the Tokyo Bay Waterfront and over the Rainbow Bridge (see photos in the Tokyo section); I took JR's Narita Express and the Keisei Limited Express to and from the airport; I rode JR regional lines in Tokyo, Nagoya and Hiroshima, as well as Osaka's JR Loop Line, and I used metros in Tokyo, Nagoya, Kyoto and Osaka.

Tokyo Metro, at Roppongi Station.

Kyoto Subway, at Shijo Station. As my photos of the Osaka and Nagoya subways didn't turn out (ever try to take photos in a subway station?), you'll just have to wait for my "subways of Japan" collector's series.

I did, however, take this photo of the interior of a train on the Higashiyama Line, Nagoya Subway. It's relatively uncrowded (which is why I was able, finally, to take such a picture), but it's otherwise typical of the inside of a Japanese subway car. Note the seating configuration (designed to maximize total capacity), the distinctive straps with shower-curtain rings, the digital display (there are monitors, with real-time maps and video advertising, on the Yamanote line), and the abundance of in-your-face advertising.