Nin hao Sakura,
It depends on what you want to see when you come to Japan. I think four places everyone wants to visit when they come here are Kyoto, Mt. Fuji, Hiroshima and Tokyo. Kyoto is good if you want to see elaborate temples and old palaces. Mt. Fuji people go to just because it is so popular in Japan and a symbol of Japan to the outside world. Hiroshima is a very important place because of the tragedy of the atomic bombs dropped on Japan and every human should see the memorial there to remind them why we must fight to dismantle nuclear weapons and strive for peace. Tokyo is very popular just because it is the capital and has some interesting things to see.
As far as costs, it really depends on how much traveling around and eating at restaurants you will be doing. I think 10,000 yen a day may be a good budget if you find cheap places to stay every night. Then you will want maybe 40,000 to 60,000 for souvenirs and reserve money in case you spend more than you expected.
Maybe an organised tour through a Chinese travel company would be cheaper for you, but I don't know how much they charge for Japan tours.
Here is the site for Japan Railways
Japan Railways Group You should look for a rail pass, but I don't know how much you will be able to use it in just one week. Don't take taxis if you can avoid it, they are very expensive.
Good luck! Zai jian!
(Sorry if you speak a different form of Chinese, I only know a little Mandarin)