A man driving down a hillside road realizes that his car's brakes have failed. The car crashes into a toll booth, killing the man. He leaves a dying message: "Tanabata kyo." A Mahjong tile next to his body links this case to six others in Tokyo, Kanagawa, Shizuoka, Nagano, and other Japanese prefectures. Because of the Mahjong tiles left beside each victim, the police conclude that the same person or organization committed these murders. The police across Japan unite to solve the serial murder case.