Rikimaru survived what everyone thought was certain death. After Lord Mei-Oh's defeat in the previous Tenchu entry, he was left buried under a collapsing fortress—but the report that reached Lord Gohda a year later was that Rikimaru had found a way through. What neither Gohda nor Ayame know is that the man who survived is a duplicate: the real Rikimaru is stranded in the twentieth century, working to find his way back. The plot across both characters centers on the Three Jewels—Heaven, Earth, and Virtue—coveted by the evil wizard Tenrai, who commands a force that includes the serpentine Onikage. Onikage serves Tenrai not out of loyalty but in pursuit of his own goal: resurrecting both the fallen lord Mei-Oh and Tatsumaru, former leader of the Azuma Ninja.