First Trip to Japan – Itinerary help

Wanted to get a rough idea from more experienced travelers. Traveling to Japan for the first time and I feel completely lost. wondering if I'm trying to bite off more than I can chew.

I have a total of almost 10 days in country.

arrive Tokyo Sept 29th afternoon

Sept 30 – Oct 3rd Tokyo (4 days)

Oct 4th-6th Kyoto (3 days)

this leaves me with 7th, 8th and 1/2 day on the 9th (presumably in Tokyo) which are open and not sure how to maximize.

I've been reading through some threads and wondering if I should add Hiroshima (I'm a history buff), or places like Osaka, Kanazawa. If I did that would you just use Kyoto as a base and train it to those places?

I know its a basic question so appreciate the help in advance.

by shadowline74