Osaka, Kobe, Kyoto, Tokyo

Hi,
You really don't give enough information. Are you leaving Japan out of Osaka or Tokyo? If Tokyo, a full JR Pass would not be cost effective for your plans. You'd then need to buy regular fare tickets, but for your time in Kansai (Osaka/Kyoto/Nara/Kobe) you could save some money using some regional passes. Have a look at:

http://www.japan-guide.com/e/e2357.html

If you do leave Japan out of Osaka, then with a couple of side trips, a 7day would pass off. Visiting Himeji would fit the bill nicely. Visiting Nara wouldn't help much but you shouldn't omit the place from your itinerary - it is wonderful.

Good luck!

I will arrive in Kansai and leave in Narita
So should I get the JR. pass? I'm going to Japan in end of July
Do I need to book the Bullet train ticket from osaka to Tokyo first?
Or I can just buy it from the station?

Thx

Hi,
As said, a JR Pass would not pay off if you are leaving out of Tokyo with your itinerary.
For buying the tickets, you can easily do so at the station. You can see rail schedules and fares on Hyperdia .

For your time in Kansai, some regional passes might help depending on your plans. Have a look at:

http://www.japan-guide.com/e/e2357_005.html

Thank you so much for your advice
Really appreciated!!