Hi there,
If you're after a fun trip, you are in luck: the journey from Tokushima to Hiroshima is excellent (and totally possible with a Japan Rail Pass, but more on that later).
As Tokushima is on Shikoku, you'll travel over the Seto Ohashi bridge (the world's longest two-tiered bridge system) to get to Honshu. From Okayama you'll be able to travel on the Hikari Railstar or Sakura shinkansen bullet train to Hiroshima - exciting stuff. Here's a sample itinerary from Tokushima to Hiroshima and from Hiroshima to Osaka.
Here are the basic adult ticket prices of your trip:
- Tokushima > Hiroshima: ¥9250, (191mins, 307km)
- Hiroshima > Osaka: ¥10220, (109mins, 345km)
TOTAL: ¥19470 for 2 legs
(please note that if you are travelling with children under 6 they travel for free, and under 12 travel with 50% off).
As the ticket price of this trip is ¥19,470 and a 7 day rail pass comes to ¥28300, unless you intend to do more travel, I would advise you to purchase individual tickets for this trip.
Hope this helps!