Kamakura is easy to reach from different directions and depending on what area you'd like to visit you can choose from various stations. The bets way to get your info is visit the website of the Japan Railways: www.japanrail.com
When you've arrived, Kamakura's interesting spots are quite easy to walk to.
From my hotel, when I go out, I learned from my experience that I will not get lost again. I alway go to Yokohama Station at the Tourist Information Center and get important detail to reach for my destination.
From Yokohama Station it will take 30 minutes to arrived in Kamakura Station. ( I can not remember what is the name of the trains ).
From Tokyo, take the Yokosuka line train to Kamakura. The journey takes about an hour & cost about 1000 Yen.
NEW TOKYO INTERNATIONAL NARITA AIRPORT: Click Here
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I took the train on my own. It was easy to get here but not as easy to get around unless one speak Japanese. Try to follow the crowd, that's one way to get to tourist attraction :)