Japanese Street Fashion is the term for all the original and crazy fashions you'll see people in different parts of Japan.
Tokyo itself is known for many different styles and trends. In Shibuya and other trendy parts of Tokyo, you can find the gal/gyaru/ganguro/yamamba style (google it) and in Harajuku you'll find lots of cosplayers, visual kei fashion, gothic lolita, punk, decora, etc.