In fact, not just Tokyo, Hokkaido in Japan is also a wonderful place. I have been there two years before, and it is in summer. There are lots of beautiful lavender in the fields, and you can buy lavender cushions, lavender candies and taste the delicious lavender ice-cream ! Well, I really want to taste that ice-cream again! Besides, Hokkaido has a lot of special, tasty food, like chafing dish with the crabs with very long legs ,Rahmen Noodles,'Hidaka beef' and 'Shiraoi beef' , 'Jingisukan', a popular Hokkaido-style barbecue... Yummy!
Also, you can visit the bear ranch and have a hot-spring bath in Hokkaido!
If you want to know more about Hokkaido, you can go to the following web-sites:
http://www.japan-zone.com/omnibus/hokkaido.shtml
http://kanko.pref.hokkaido.jp/kankodb/foreign/e/trv_i002.htm