I actually wouldn't recommend this. Even if you take the 7.20am bullet train from Kyoto getting into Hiroshima at 9am and then you start making your way towards Miyajima around noon... imo you want ~6hrs or more from the time you get off train at Miyajimaguchi until the time you get back on the train. Trying to catch a 5~5.30pm bullet train from Hiroshima would make for a rushed trip imho. Plus, having to tow the suitcase around on the last day... what if all the large lockers are occupied, etc, etc... too much to worry about when you're about to catch a flight that night.

Most of the large luggage lockers were open at that time of the morning and were very easy to navigate. We were on our way in a few minutes and on the island a little after 10. We explored the temple, took the ropeway up, hiked down, had lunch, and did some souvenir shopping before taking a ~2:00 ferry back. Train+tram to the peace park was 45 minutes, ~90 minutes at the park+museum, and a 10 minute ride back to the station.

To each his own, I'm just offering an alternative that may make more logistical sense, as it did for us. Certainly a busy day, but I didn't feel like I was rushing through everything. (For a few extra minutes, there's a 5:45 train arriving KIX at 8:30.)

Thanks, Linglingfool and Evergrn.

I'm planning to send my suitcase directly from NRT to KIX and pick it up at the airport on the day of departure. That way I'll be able to travel just with a bag pack (REI GrandTour) and not worry about towing any luggage.

That said, I usually don't like to rush on the last day and I'm allocating that day to explore Osaka. Since my flight leaves around 10pm, I'll have a full day to see Osaka or even take a short side trip to Kobe early morning. That will also be my last day of JR pass so it'll work out well and I can get to the airport early evening to pick up my bag.