Genmaicha (brown roasted rice tea) - is usually a blend of bancha or sencha green tea and roasted rice. This blend combines the tart notes of green tea with the nutty flavor of roasted rice. The Japanese, in keeping with their long tradition of drinking genmaicha tea, consider it a variety of Japanese green tea, not a blend.
Roasted rice is usually mixed with green tea in a 1:1 ratio, although the ratio can vary from manufacturer to manufacturer.