Also please remember that there is half country south of you that you are not seeing.
In addition, there are other numerous great places you can visit in the area. Okayama is not far and it is famous for its castle, plus Korakuen, one of Japan's Top 3, and also the Handayama Garden. If you'd like to get off the beaten trail for a while, the half day hike up to Konpirasan in Kotohira is breathtaking. Going to Takamatsu is also good - it has one of Japan's best gardens also, named Ritsurin.
Hiroshima also has a number of good places. Miyajima is the most famous, and aside from Hiroshima itself, Onomichi with its temple tour and Kosanji Temple is spectacular. Just beyond Miyajima also lies Iwakuni with its historical bridge and mountaintop castle. Taikodani is also a superb shrine in Tsuwano, Shimane.
Hagi Castle was actually delightful, and the preserved samurai district and Mori related temples a rarity. One of the very best is the Akiyoshi Limestone Cave, a 300 million year old marvel with massive open caverns and an underground river running through it.
If you can, try to find a little time to see the Japanese themselves. Go visit a Japanese supermarket and see what people typically eat. Look through a park and watch the Japanese kids play. Learn about the history of some of the places you visit before your departure - it will give your trip so much more meaning.
In total, there is certainly a lot more to explore and enjoy.