Sima Yi

The Wei strategist, Sima Yi was studying, when he heard that Wei was looking for a stratigist. Sima, who knew he could use his talents to rule the land one day readily accepted.

Role in Plot
In Dynasty Warriors 6, his storyline revolves around him using Cao Cao's ambition as a means of gaining control of the land by any means neccesary. In his final cutscene, he is shown slaying Cao Cao, and ascending the throne.

Kessen
Sima Yi is a confident and talented magician for Wei in Kessen II. He is first seen strutting into Cao Cao's throne room midway through the game, wondering why he can't find the "great hero of the land". He bluntly ventures that Cao Cao is the cause of the land's natural disasters as they continue due to the conqueror's selfish desires. He states that the lord will lose to Liu Bei if this continues, which gets an angered response from Cao Cao. Sword drawn to the offender, he growls for his name to which Sima Yi politely bows and introduces himself. Cao Cao likes the sorcerer's fearless nature and recruited him on the spot. His battle strategy is the best way to fend off an angry Ma Chao.

Quotes

 * "Lord Cao Cao, observe those around you. You have more loyal commanders than the sky has stars. They have pledged their lives to you yet you do not realize this. No, you're only thinking of yourself. Your glory, your supposed greatness."
 * Sima Yi; Kessen II

Dynasty Warriors 4
Defeat Ma Chao and Wei Yan
 * Ultimate Weapon: Dark Feather
 * Power: 50
 * How to get it: Battle of Wu Zhang Plains