Japan map has some special features which makes it shine and seems to be designed for this purpose - to get you into Cold War era quickly, very quickly, forget about endless research to reach Cold War, this is the way. All you need is actual access to Japan map - 40GPs count and ability to play it, if you have supporter pack, you have the ability unlocked.

At the start, you should just spam the huts and locate Mount Fuji natural wonder and build Petra next to it once you can build it. It will slowly gain you extra warp, with festival on, double amount of it.

Aim your research to get to Religion tech in Classical age as soon as possible.


Once researched, you can build Itsukushima Shrine and Luxor Temple.
Build both of these wonders. Itsukushima Shrine will give you science to pick a new tech in next era once you finish all the research in the current era.

In Luxor Temple, pick Islam as your religion and finish all steps.
The last step will provide this:

By finishing Islam, you have now enough science to get the first tech in Industrial Era.
Choose Capitalism


Build the Big Ben wonder and pick Socialism as your ideology.
Focus on finishing it to get the second and third science boost.
Last 2 steps will provide this:

When you finish socialism, you are almost done with research in the World Wars era, but a little science is missing.

This is the time to build Oxford University wonder.
Oxford University will finish your last World Wars era research and thanks to the Itsukushima Shrine, you will unlock first tech in Cold War era.

Itsukushima Shrine:

Congratulations
You made into the Cold War. You may pick Skyscraper tech to build Condos and try to go further in the Cold War if you have already some Great People which boost your idle science.

My recommendation is to find a way how to quickly get some Extra Great People by increasing your Empire Value so after rebirth you have some choices of your new permanent Great People.

By reaching Cold War, after rebirth you will be rolling from the Information Age Great People pool as well, so make it count by having at least some decent number of the Extra Great People.

Examples for increasing your Empire Value:

• Start mass production of Battleships or Submarines(better choice) and engage your accumulated warp.
  
• Make some profit trades - there can be great opportunities on the player market in your caravansary, so check it out.
  
• Collect tariffs

Once you are satisfied with your Empire Value go rebirth and repeat this whole process again.
Its doable within few hours, depending how quickly you can reach Religion for example and how quickly you can finish Islam and Socialism.

Your next runs will be faster and you learn few things how to speed up the process, go ahead and try it.

BEST OF LUCK TO YOU

Feedback would be appreciated, feel free to comment on anything in this guide, your thoughts, what you dont agree with, what would you change etc.