Month in Japan

Hi there!

Its a very nice plan and very similar to one I made this April. You will be a lot on the train though :)
A 21-day JR Pass would certainly make sense for this, a return to Sapporo alone will pay for the greater part of the pass, so you will make some impressive savings with the rest of your itinerary.

Activating it at Narita is totally fine. You can exchange the pass, once you are in Japan and select the first day of use up to 30 days in the future and selecting the date that you travel to Kyoto would indeed make the most sense. You can also activate it at one of the exchange stations in Tokyo, Narita can be someone busy and an other station may be faster if you have the luxury of time. The process itself in done within 5 minutes given that there is no waiting queue before you.

I really like the idea of going all the way down to Kyushu (Kumamoto, Kagoshima), it has always been my favorite region in Japan. On your way back to Tokyo, you could cut out some time and costs by taking a night train from Okayama. A basic seat on the Sunrize Express is covered by the JR Pass and it makes for a great experience. You can also exchange Yokoyama on the 3rd of July from Tokyo, in case you already have seen enough of Tokyo.
I saw that you plan days in Aomori, it makes for a good stop over if you travel on the Hokkaido the next day but there is little of interest in the city itself. Instead I would recommend staying the time in [Hachinohe] and/or in Hirosaki. Alternatively you can just get the travel out of the way by going straight to Sapporo (just 2 days in Sapporo is rather short).
On the way back to Tokyo you also have the option of taking a night train (at least partially). The Hamanasu express rides between Sapporo and Aomori and the Akebono train rides between Aomori and Tokyo. Both are covered by the JR Pass. I would also recommend a stop at Hakodate if you have time.

A word about night train, they are very popular and it will be impossible to book them on the day of departure. You can however book them the moment that you exchange your JR Pass (even if the first day of use is in the future). So i would recommend going so at that moment.

Lastly, when you arrive at Narita Airport and travel to Tokyo, consider buying a [Suica + N'EX] package, that gives you a discounted ticket on the Narita Express to Tokyo and a Suica card that really comes in handy when you travel around the city of Tokyo, you can for instance use it to pay the fare to Kamakura.

For the rest: You are good to go!

Make the most of your great trip!
-Daniel

Daniel-san,

I hadn't considered night trains before, but it sounds exactly like what I'd want to use. Thanks for bringing that to my attention! I recognize Aomori isn't a tourist hot-spot; it's to visit friends, but I'll see about nearby locations to see about making a side trip as well.

Thank you for all the insight regarding everything else, too!
-C