A mysterious monster called the High Beast has taken control of the regions of Eurasia and Africa. Japan has cut off from the mainland to protect itself from this threat. The daughter of a legendary mahjong player discovers that monsters attack whenever a mahjong piece is hit across the board. This allows humans to be separated from the battle and for mahjong players to effectively combat the monsters with robots controlled through mahjong moves.

(Source: Getter Robo Wiki)