Decide what this side trip is meant to add
Hiroshima and Miyajima are not just extra stops after Kyoto and Osaka. Hiroshima adds historical depth and a peace-centered perspective. Miyajima adds landscape, water and one of Japan’s most iconic shrine settings.
Day trip, one night or two?
A day trip can work if you accept a long, structured day. One night is the strongest standard answer if you want both. Two nights are worth it if this is a major part of the trip or if you want to stay on Miyajima.
When to skip it
Skip Hiroshima and Miyajima if Tokyo or Kyoto are already too short, or if what you really want is an onsen or Fuji-area contrast rather than historical depth.
When to get personal help
Personal planning is worth it if you are choosing between a day trip and an overnight stay, or trying to add Hiroshima and Miyajima without making Tokyo or Kyoto too short.