Question

i am going to visit tokyo for 4 days should i buy JR pass?

Location

City: Tokyo

Prefecture: Tokyo

Country: Japan

Answers

I don't think so, but I think getting Suika card (IC train card) will work well for 4 days in Tokyo.
4 days is too short to fully utilize the pass. You might want to get a day pass of Tokyo Metro while you move around in Tokyo.
Mr Wong is Right! And if you're a visitor from overseas and arriving via Narita, you can get even cheaper day passes (with or without Keisei Skyliner passes).
Check out the 'For Customers from Abroad' page on the same site he mentioned:
I agree with everyone else. The JR rail pass is really useful if you want to visit some places using the shinkansen (bullet train). If you are not planning on visiting anywhere else, don"t waste your money. Besides the Tokyo Metro site, you can also buy cheap tickets at various shops around Tokyo. One of the more famous chains is DAIKOKUYA. They have many locations and you will usually save about 15% on any ticket. Here is a link, but it is in Japanese only :
Unless you are planning a long trip somewhere (like to Kyoto) it really doesn't make sense. Another thing to consider is that it only covers Japan Railways not private railways or subways. If you are going to be in Tokyo the whole time, it might be better to buy a one day subway pass.
If you're talking about the JR train pass that allows you to ride any JR line, yes. The JR lines are very convenient for getting around Tokyo. However, you cannot ride subways or other private lines with the JR pass, you can only ride on JR lines. It's a bargain.

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