Unsure about Rail Pass

Hi,
We are flying into Tokyo on the 2nd May, and flying out from Hiroshima on the 26th May. Not really worked out an itenarary yet, but vaguely around
5 or 6 days in Tokyo Inc day trips,
4 or 5 days in Kyoto Inc day trips
3 or 4 days in Osaka Inc day tripa
2 days in Hiroshima on the way out.
Was hoping to go to Hokkaido but unsure whether we could budget that cost.
Would a rail pass be cost efficient, or would it be more cost effective to purchase rail/bus tickets as and when.

Thanks Mike