My suggestion will be for you to make a couple of day trips to Kyoto, or if you can, stay in Kyoto for a couple of nights. Kyoto, in my opinion, is one of the must see places in Japan. Enjoy the Kinkakuji, Ginkakuji, Byodo-in, Tofukuji, Inarisan, Kiyomizudera and the numerous other temples/shrines.

Another day trip worth making is to the ancient Japanese capital of Nara. It can be a half day trip and I think you will enjoy the laid back atmosphere and the historical sites there.

If you have time, make an overnight trip to Kobe and try to enjoy the hot springs of Arima Onsen. An onsen experience is again in my opinion, a must for any Japan visitor.

As for food, Osaka is the food capital of Japan. Try the Kaiseki dinner and the other mom and pop stores in the Nihonbashi and Namba areas. The price varies all over the place, so use your wallet to guide you. Remember, Osaka natives are crazy about their Takoyaki, so enjoy them from the street vendors. If you like crabs, then the Kanidorku is a great place to eat. It is slightly expensive but was very much enjoyed by me the last time I was there.

If you are into sushi and are feeling adventurous, then I recommend that you visit a sushi place and order their Omakase or Chef's special. It is usually an adventure for me because there are usually items that I have not had before. These are exotic seafood that are fresh and in season, which the chef had selected to order that week.

Osaka is also the capital of the "hentai" side of Japan. Most of these places do not accept foreigners, but there are some that will let foreigners in, but for a premium of course.

Above all, have fun!