Player assumes the role of the younger brother of one of the biggest names in Supercross who was hospitalised in the final race of the World Championships in an intentional move by Team Nemeshisu.
Players take their brother's place at team Yamaha and, with their brother's help, work up through the ranks, to become World Champion and avenge his foes.
Source: Wikipedia, "Yamaha Supercross", available under the CC-BY-SA License.