Promoted as the final release in the series, Onimusha 3: Demon Siege looks to surpass its predecessors in areas such as gameplay, art, and technology, to become the premier installment of the Onimusha series on the PS2 console. Reprising his voice-acting role as the lovelorn samurai Samanosuke Akechi is Takeshi Kianeshiro. Joining him is renowned French actor Jean Reno, best known for his roles in The Professional, Big Blue, and La Femme Nikita.
The game opens at the Honnoji Temple. Samanosuke continues to battle the demons in his path until the moment finally comes when standing before him, ready for battle, is the undead Warlord Nobunaga Oda. However, before this epic clash can begin, Samanosuke suddenly disappears.
The year is now 2004. An otherwise peaceful French metropolis finds itself under attack by demons. Unleashing an unimaginable horror, the Genma demons go on to slaughter civilians and soldiers, one by one. From out of this fury appears a French soldier who stands up against the Genma demons, Jacques Braun (Jean Reno). Deployed to this scene of carnage, Jacques quickly finds himself surrounded by hellish enemies. Then, in the distance, an ancient samurai warrior inexplicably appears, to help fight off the demons and save the city.
The two begin slaying demons together, until Jacques is suddenly caught in a mysterious vortex, eerily familiar to Samanosuke, and is transported to feudal Japan, leaving behind Samanosuke in modern-day France. The question now stands, why has Samanosuke appeared in present day France, and Jacques in Feudal Japan?
As players attempt to make sense of this strange scenario in the beginning of the game, many advancements and new technologies may also come to their attention. For the first time, fully 3D backgrounds are featured, and dynamic camera angles add a sense of depth during battle scenes. New environments have been added, including Paris landmarks such as Notre Dame and the Arc De Triumph, though also included are familiar backdrops such as Anshi Castle and Honnoji Temple.
Powerful swords, capable of destroying enemies with one blow, are available, along with new weapons that add additional challenges. A whip weapon, unique to the Jacques Braun character, is handy for combat situations as well as exploration. With its ability to latch on to objects, players can use the whip to swing across various platforms and access new areas.