Hi,
Also, if flying out of Hiroshima airport and it is a nice day, I would consider getting to the airport early and visiting the Sankeien garden
Sankeien Garden (Mihara) - Hiroshima Attractions - Japan Travel
It is a 5min walk from the airport terminal and was beautiful in may ( apart from people feeding the carp at the entrance, I was the only person in the garden- beautiful for an hour)
The airport also has an outdoor observation deck ( land side)
Regards
TBS