Travel suggestion on summer vacation

Hi friends. I am recently married and currently residing at Yokohama Japan. We are searching for travel destination for at list 4-6 days between 8th to 16th august. As I have Japan driving license so want to explore the locality of that place by rent a car. I also have my own car so any suggestion about driving from my place will be also appreciable. My budget for the trip is 100000 yen. Thanks in advance. Looking forward to hearing from you guys.

100000Y? Maybe not enough.
BC in Obon[‚¨–~] week is travel season peak�@as one of 3 peaks of a year.
(Golden week,Obon week and Year/end-New Year holidays week)
Good location and cheap hotels/ryokans are already booked usual.

Also traffic jam a lot by travelers cars usual.
Yokohama(as Tokyo area) is about 32 million living
and eascape too hot too busy urban life and back to home country usual.
So not so mnay comfortable good spots (even escape Japan/Japan out a lot)
and still no reply means very difficult Q for answerists.

Click each regions.
http://travel.rakuten.co.jp/vacancy/august/
Large numbers left areas are not still busy. (use google translate/map)

100.000 yen might not be enough unless you stay in the region and just drive around Yamanashi Prefecture (Fuji Lakes) or go to Izu Peninsula (Shizuoka) ... or something like that ...

Or how about climbing Mt. Fuji?

But for summer I recommend Okinawa or Hokkaido (though that's both rather expensive).