trains going through continuous urban areas?

I was a bit disappointed when I took the bullet train to Osaka because I thought it would be all continuous city/suburbs all the way but it was actually quite broken up by rural area, at least it looked like that. Do local trains on the Tokaido main line pretty much follow the same route? If not, is that what I'm looking for in order to see non-stop cityscape out the window? What other areas could I travel to in order to see this? (Am guessing Nagano, Utsunomiya and Takasaki? - they all look pretty non-stop urban on google earth)

Do local trains on the Tokaido main line pretty much follow the same route?

Yes, the Tokaido area is pretty much completely urbanized except for some tea fields around Shizuoka.

What other areas could I travel to in order to see this?

Pretty much any other area of Japan outside of Japan's three major metropolitan areas and the Tokaido/Sanyo Shinkansen. Generally speaking, shinkansen are not ideal because they use a lot of tunnels even when they go through rural areas.

Am guessing Nagano, Utsunomiya and Takasaki?

Towards Nagano it gets rural, but the lines to Utsunomiya and Takasaki are pretty urbanized, although the number of rice fields increases halfway through.

I recommend taking the Chuo Line from Tokyo to Nagoya. Or the Tohoku Main Line up into the Tohoku Region. Or follow the Sea of Japan coast.

The routes are different, but it is not continuous - depends a bit where you are. Maybe you are after something like the area within Chiba, Saitama, Yokohama cities (with Tokyo and Kawasaki in the middle).

You mean to say you were disappointed that you didn't see continuous cityscape/suburbs from Tokyo to Osaka?

I'd be disappointed if that's ALL I saw.... You don't like the countryside of Japan?

for a non-stop cityscape out the window take the Yamanote line.

"for a non-stop cityscape out the window take the Yamanote line" in Tokyo.
and take the JR loop line in Osaka..

I'd say it would be better off not using the Shinkansen if you want to see suburbs all the time.

Any commuter line in the big cities, Tokyo, Kyoto, Yokohama, etc would opt for seeing suburbs. With Tokaido shinkansen you get to see some suburbs yes but then it is naturaly rural areas, because I think they avoid building high speed railway through populated areas unless they want a station there or something.

I dont really see the reason for wanting to see urban areas though....

He likes concrete. Don't judge the man. We all have like others dislike.

There was this film called, "X-Men Origins: Wolverine" that shows a sword fight on a Tokaido Shinkansen running at full speed, mind you, through Tokyo that seemed to run forever. For someone who's never ridden a bullet train or been to Tokyo, they might get the impression that the shinkansen runs at full speed in the cities (only 100kph allowed) and that high-rises is all you'll see (incorrect as well). I don't know (I hope not) if this is the case.

For those wondering why on earth I would want to avoid rural areas, in Australia you can only travel perhaps 50km outside of a major city without leaving suburbia (by train anyway) so I'm fascinated by traveling for hours and seeing unbroken city after city outside. Kind of like Bladerunner or Coruscant... to me it's just as unique an experience as indulging in everything else unique that Japan has to offer.

Well you'll get a surprise then. Japan's urban areas are not as spread out as Australia. They do upwards, not outwards like Australians do. You are not gonna find what you are looking for in Japan.

Oops I forgot to add. Shinkansen are worst for seeing the scenery. Too fast with stupid little windows. Take a local service and enjoy 60-100kph speeds and huge windows. You'll see a lot more.

I too was surprised that the view out the train window was so rural - from google earth I expected vast areas of urbanisation/cityscape This was because I saw grey concrete spreading across the plains between forested ranges on the screen . But when there, much of my 'concrete' had turned out to be leaves. It was a real surprise!

When I came home, I wondered how I had formed such an incorrect view, so I zoomed in on google earth to find out most of the grey area was rice paddies or fields, and even that much of the grey developed area was interspersed with paddies and fields. These were very green in September.

This was a pleasant circumstance for me, as I like the country more than the city, and a key purpose of travel for me is to encounter not only the unfamiliar, but also the unexpected.

It is a assumption many foreign travelers make. I did it myself also. You here stories about concrete jungles etc about Japan. And when you arrive, you see otherwise.

Obviously, I misunderstood your question.

Now that I understand it better, I recommend to take the Shonan Shinjuku Line or the Ueno-Tokyo Line from somewhere around Hiratsuka to a few stations beyond Omiya. Use a green car where you can sit forward-facing with nice large windows. For about two hours, you will be traversing the world's largest urbanized area. Lots of concrete and very little signs of the countryside.

LOL. Of course Japan isn't continuous buildings and urban centers. They need space to grow food in as well!