Hi there,
The best thing to do here if to look at ticket prices and see if a JR Pass can be a good match.
Tokyo - Kyoto ¥ 13,600
Kyoto - Hiroshima ¥ 11,090
Hiroshima - Hakuba ¥ 17,530
Tokyo - Kanakura (return) ¥ 1,840
Kyoto - Nara (return). ¥ 1,420
For a total of ¥ 45,480. The price of a 14 day JR Pass is ¥ 46,390. As you can see, the prices are very close. That is not to say though that the JR Pass would not work. Keep in mind that the JR Pass gives you unlimited travel and almost any additional travel would help you make savings. Then there is convenience, the pass will work as a single ticket for all your travel.
Additionally Hakuba - Tokyo is ¥ 13,130 using the Shinkansen. This is almost the same price as an upgrade to the 21 day JR Pass. So using a 21 day JR Pass is also a possibility. It would also be easy to make side trips from Hakuba, if you desire so.
Hope this helps,
Daniel