There are multiple routes for first time visitors to enjoy Tokyo, Osaka areas even without Kyoto. However, everyone should consider visiting Miyajimacho/Istukushima and Hiroshima at least once in their lives because each of them is so unique and has world heritage that no one should ignore as world citizens. We will cover the 2nd half of our day trip in Hiroshima here.
The fastest way from Miyajimacho/Istukushima to Hiroshima, and to Peace Memorial Park directly is to take the boat at the port next to the one that connects JR Miyajimaguchi Station and Istukushima island. It takes only 45 minutes at 2000 yen one-way ticket. The boat is much smaller and faster than the ferry earlier (details can be found at this website). Ticket is a pink card with one side in Japanese and the other in English.
When it's over half way, getting close to Hiroshima city, the captain will open the door for passengers to get to the deck so everyone can enjoy the view outside, which is quite pleasing despite some strong wind. The captain will share stories and quick introduction about the surrounding areas but in Japanese only so we didn't understand too much. We would recommend to bring some simple snack to the cruise trip as you will spend 1st half inside viewing the waves and oceans from inside.
The cruise gives you an angle to see Hiroshima that land route won't provide. Hiroshima is such a beautiful city that you might forget the terrible history happened here before. World Heritage Site in Hiroshima is the Peace Memorial - known around the world as the Atomic Bomb Dome. It's the only remains stayed since August 1945 after 'Little Boy' dropped. The cruise port was 2-3 minutes walking distance from the remains. We didn't get into the museum as it was closed for earthquake maintenance so highly recommended here for any tourist sight, checking open/close time before you go is really necessary.
When the main museum was closed, visiting Hiroshima National Peace Memorial Hall for the Atomic Bomb Victims was a nice alternative to learn about the history and its impact years after. All the main sites are within walking distance to each other in the Memorial Park area. Bus transportation is very convenient if you'd like to go from JR lines, train station or airport, etc. You do need to carry cash so that it can be changed to coins on the bus by using the machine next to the driver.
We took the bus back to JR station to return to Osaka. We had some great late night red bean paste snack-Taiyaki on the way back. We are really grateful for the peace now. As the prayer you can see in multiple places in Hiroshima, may the peace be with us globally. May we never make the same mistake again. Let's love each other more.