The Omen is a mysterious spirit who frequently haunts Jack. He resembles a ghostly black silhouette of an armored samurai with glowing eyes riding on a horse, surrounded by an ominous green fog. Up close, he appears to have no visible face and a hangman's noose around his neck. He also has a deep, dark voice. It is later revealed that the reason he haunts Jack is because he has neglected his purpose as a samurai, and insists that he commit ritual suicide of seppuku.
Very little is known about the mysterious spirit, except that he stalks Jack at various points; it can be noted that he always appears whenever Jack has feelings of intense guilt or doubt in himself.
The Omen first appears on the other side of a stream, after Jack hallucinates seeing his parents and multiple corpse-like people. The area becomes black and the rider appears with a ghastly green background, shocking Jack as he glares menacingly at him. The Warrior appears again that night, as Jack is tormented by a hallucination of his Father in flames, after which his signature horse whinny alerts Jack to turn around and see the Omen again, imprinted on a rock. The next day, in the middle of Jack's battle with the assassin Scaramouch, the spirit appears on a nearby hill, watching Jack's hallucination of the city's slain children.
Later, the Omen appears a fourth time as Jack hides inside the parts of a previously destroyed Beetle Drone. As one of Jack's hallucinations of himself pleads with him to "join his ancestors", Jack turns to look through the crack of the Beetle Drone's shell, only to see green mist surrounding the area and the Omen staring at him. Jack manages to see past the Omen and his misty fog, therefore finding a temple to seek refuge in.
After being grievously wounded and narrowly escaping from the Daughters of Aku, Jack tries to find shelter in a forest, only to turn around and notice the Omen waiting for him. Jack tries to ignore the spectre, but discovers that its mount can move. As Jack continues his search for shelter, the Omen refuses to be ignored and continues to stalk Jack while still on horseback, never taking his eyes off him.
Inside one of Aku's factories, the Omen seemingly claims victory as he notices Jack's grief over the unconscious kidnapped children (who Jack believes to be dead) and speaks to him for the first time, telling Jack "It is time". A broken Jack simply answers "yes" and follows the spirit out of the factory, leaving Ashi and the children alone.
Ashi finds the Omen encouraging Jack to commit seppuku (Japanese ritual suicide) with the spirits of four armored samurais, presumably Jack's ancestors. He attacks Ashi when she tries to stop him, but upon hearing the truth about the children, Jack intervenes and duels the Warrior. After a brief fight, Jack vanquishes him and the samurai spirits return to their graves.
Given that he is accompanied by four samurai spirits, it is possible these five are in fact Jack's ancestors. Jack's hallucination once told him that the spirit of their ancestors were waiting for them.
- "It is Time"
- "You may witness, but you cannot proceed any further [...] The End"
- "Great warriors of past, I will commune"
- "This Samurai has failed his purpose, and has accepted his fate"
- "This does not concern you. There is no hope"
- Hope is just a fleeting sentiment. You're failure is real. You must face the consequences, or continue to bear your guilt of your dishonor, for all of eternity"
- "Death falls in your wake; Men. Women. Children. Yes, all those children dead, because of you".
- "NO MORE WORDS!"
- The Omen might be considered as the samurai version of the grim reaper or death.
- It is possible that the Omen is really or at least based off of a Shinigami - a god of death present in Japanese religion and culture. It is considered the Japanese equivalent of the reaper itself.
- The Omen bears a almost striking resemblance to Jack at the beginning of XCII, His samurai armor is the same and he wears the same rope-noose (presumably used to tie a beard).
- The Omen appears of slim weight when he is in silhouette form, but after dismounting his horse and confronting Ashi, he is of a much more bulkier weight.