Locations around Yashio, 2 hours

Hi!

I'm looking for some recommendations what to do (and maybe what not to do). I prefer hiking (high moderate to low expert routes), nature and photography. But would be up for anything else as well like festivals. Though I prefer off-tourist spots.

I'm going to stay in 八潮市 from September to October. I still need to plan for the time from 9/14 - 9/15, 9/25 - 9/28 and 10/1 - 10/2, so 8 days. I will have a rental car but no rail-pass.
I'm willing to drive up to ~2hrs thus I can be at whatever place to 10am so there is enough time until sundown. (and be back when my gf finishes work at about 7pm)
This means either whatever spot I'm going to is relatively close to Yashio or is close to a highway for quick access.
Checking Google Maps it seems I can go north up to about 白河市 Shirakawa, west to 軽井沢町 Karuizawa, south to Mt. Fuji and full Chiba prefecture to the east.

I made a map with spots I already visited and where I might visit.
https://drive.google.com/open?id=1ywconLWK2I8lvJQKPo1Ar1wjgOJyG9l1&usp...
I have been to Tokyo in 2015 for a week and have seen most of what I would like to see (parks, museums, ...). So except there is something new since then, like the MORI building, I might not be interested in that area.
I wouldn't mind driving around japanese style though. I.e. I thought about driving along the east cost in Ibaraki.

I'm very grateful for any recommendation.
よろしくお願いします。