A young reporter, Kotaro Rai, is on the trail of a ring of gem thieves. But Rai is faced with an evil that threatens all of Asia, the Zensei Majin who had been in disguise. Luckily, the man's life is saved by a good spirit named Diamond Eye, who had appeared from one of the stolen diamond rings. From that day on the diamond hero entrusted the ring in Rai, and when he's in need of help, Diamond Eye would appear and protect him.