Tenrai is a powerful wizard and the main villain of Tenchu: Wrath of Heaven, he leads an army under the affiliation of Lord Mei-Oh and uses his magic to bring back several deceased characters in the Tenchu series most notebly Tatsumaru and Onikage. Tenrai wields an array of dangerous spells: lighting bolts, ice spikes, and teleportation. When he is defeated by either Azuma ninja he becomes more powerful and transforms but it in different ways depending on who the player is controlling. In Rikimaru's mission Tenrai gains a dark aura around him and fights with dark energy spheres and a powerful throw move. In Ayame's quest Tenrai's second form is more demonic looking and uses lunging physical attacks occasionally stopping to emit a poisonous green mist. Depending on the character chosen the basic story is significantly changed but both result in a final confrontation with Tenrai at his fortress ending with his death at the hands of the player.
In Rikimaru's story Tenrai makes several attempts to recruit Rikimaru to his cause while keeping close observation on the Azuma ninja while the events of the game unfold. He revives Onikage who battles with Rikimaru in the Limestone cavern and at Tenrais fortress and he even revivies Tatsumaru to kill Rikimaru. Tenrai orders one of his men to take the form of Ayame and attack Lord Goda resulting in her imprisonment to lure Rikimaru to the Bamboo forest to serve as a destraction while his forces attack the Buddaah Temple under the command of Kagura and Ganda. Rikimaru arrives and kills Kagura with Ganda being killed by Tatsumaru, after a short battle Tatsumaru reveals how to defeat Tenrai. Enraged by his betrayal Tenrai kills Tatsumaru by extinguishing a candle which represents his life force, Tenrai attempts to recruit RIkimaru one more time before inviting him to avenge Tatsumarus death by attacking his fortress. Rikimaru confronts Tenrai and is shocked when his attempts have little effect and watches as Tenrai absorbs the power of Mei-Oh to fight RIkimaru. Rikimaru is blinded and battered by Tenrai but unlocks the hidden power behind his right eye revealed by Tatsumaru and fights Tenrai. Ayame comes to Rikimaru's aid after another battle and recovers his sword giving Rikimaru the strength to kill Tenrai in one last fight.
In Ayame's story the wizard Tenrai is after three magic jewels which hold great power, using an unknown assailant he recovers one of the jewels in the first mission from the merchant Nasu and Echigoya. A member of his army Hamada holds Lord Goda hostage seeking the jewel of Virtue but he is killed by Ayame forcing Tenrai to posess his body and express his desire for the three jewels prompting Ayame to search for the others before Tenrai. Eventually Tenrai gains posession of a second jewel forcing Lord Goda to send Ayame to Tenrai's fortress through a secret entrance in the limestone cavern to assassinate him. Ayame recieves a pair of sister bells from princess Kiku before her mission which are later revealed to be crafted from the Jewel of Virtue for the purpose of negating the power of the other two jewels and preventing their misuse. Ayame defeats Tenrai forcing him to absorb the power of the jewels but to his surprise Ayame still defeats him prompting him to offer his body and soul to Lord Mei-Oh through a portal, just then Tatsumaru and Rikimaru arrive to assist with Tatsumaru leaping into the portal with explosives while Ayame and Rikimaru flee the fortress.