kja

japan-guide.com really is a great resource:
https://www.japan-guide.com/e/e2160....tion_spot_list

Adastra2200

Yes, by all means tailor it according to your liking. That's why I almost never promote going on some tour - it may not be to where you want, at a pace that you like, and letting you stay at a place as long as you wish.
The above link gives the nearly all the main sights of Hiroshima City. The one question you didn't address is if you want to add in Miyajima. If so, it means being more eclectic and needing to limit your time in the city. It's important to find the right balance for you that doesn't make things too hectic nor too plodding, and regardless, you'll never see it all in one shot anyways, unless it's a small town or somewhere. In addition to what's linked to above, there is the Mitakidera Temple which JG sadly omits, plus Okonomi-Mura if you'd like to try eating some okonomiyaki there (you can also try some in Osaka, and compare the differences). If you choose to see Himeji though, you can safely skip Hiroshima castle if you're short on time.

jlee

really? I didn't know you can reserve seats on the bullet train? can you please give me more details how that works?

Adastra2200

You can certainly reserve seats on the bullet train, as well as limited express trains - for a few in fact, they are required. If you are paying for the tickets, there is an extra charge, and quite often it is not necessary unless you're traveling during a peak time. If you have a full JR rail pass, they are a free perk thrown in. For regional passes, it is case by case. You can set up a reservation at any JR office - or if you are taking a JR East train, you can do it online. You can compare the charge with and without seat reservations for example on Hyperdia - just look at the cost difference between Reserved Seat and Unreserved Seat under the Seat Fee.

kja

@ jlee: See
https://www.japan-guide.com/e/e2018.html#ticket

klandres

Thank you for the information. I hadn't seen the cost difference on Hyperdia