what kind of pass to buy

Hi there!

I think that it would be best to look at normal tickets or if you expend your travel a little a 7 day JR pass. Traveling to Hiroshima is somewhat pricey (¥ 10,350/one way) but alone it would not pay for a 7 day JR Pass, however adding a little to your itinerary could make the JR Pass become worth it. For instance a visit to Miyajima, Nara and/or Kobe would get you a long way.
The JR Pass is also valid for local travel to Kyoto and within Osaka, so all together you could be making savings fast. The main reason however I'd consider a JR Pass is that you just have one ticket for all your travel, making getting around a lot more convenient.

I hope this helps!
Daniel

Thank you for your helpful answer, Daniel. We're going to go with the JR Pass, it seems the most simplest and easiest