Outside any temple in Japan, there is a hand washing station! Before entering a temple/shrine, was hands so you enter clean. Use the wooden spoons to run the water over your hands.
At the Children's Peace Monument you can fold paper cranes just as Sadako Sasaki did. Every crane heals the world just a little bit more.
Oisters are a local delicacy. They are grown in the bay. Oister season is in february, but you can get them year round.
Read John Hersey's book 'Hiroshima' before you go. It is a small book that will help you understand it.
This stone monument says the floating torii of Itsukushima Shrine is one of the Japanese three most scenic views. (Nihonn Sannkei)