Hello there,
I would recommend a 14 day JR Pass for this itinerary! Below is a list of normal ticket prices, compared to the JR Pass.
Tokyo - Takayama ¥ 14,710
Takayama - Kanazawa ¥ 5,990
Kanazawa - Kyoto ¥ 6,900
Kyoto - Osaka ¥ 560 (or ¥ 2,810 if if you to use the bullet train)
Osaka - Hiroshima ¥ 10,230
Hiroshima - Tokyo ¥ 18,560
For a total of ¥ 56,950 or ¥ 10,560 in savings as the 14 day JR Pass is ¥ 46,390. Don't forget that the JR Pass will also cover travel from the Airport to Tokyo and local travel in many places, adding even more.
The itinerary makes for a good base plan. The current route is also without any unnecessary travel.
What you could consider going, is plan in a day trip (or two) from Tokyo and visit places such as Kamakura, Nikko or Yokohama. All make for great visits and offers much to see and do.
As for the return trip to the airport, here I would just buy a normal ticket.
Hope this helps,
Daniel