Sima Yi is a Wei strategist. He desires to use his talents to someday rule the land. His sons are Sima Shi and Sima Zhao. He generally acts as the rival to Zhuge Liang and Jiang Wei.
In Dynasty Warriors Online, he is 24 years old and his height is 177 cm (close to 5'10").
Originally introduced as a calm and gloomy strategist, Sima Yi eventually became a man who is more arrogant and conniving. He is known for his maniacal laughter and insulting friend and foe alike as "Fool!" or "Imbecile!" He doesn't truly believe in Cao Cao but is always eager to exploit every opportunity given to him. Prideful of his intellect and believing that he has an unsurpassed wit, he regards Zhuge Liang as a worthy opponent.
While usually known to be contemptuous and seemingly shallow, Sima Yi can also be easily humiliated when he can't predict the results of his actions. This mainly occurs during the spin-off titles in the Dynasty Warriors series, such as the mahjong title and Dynasty Warriors 6: Empires.
He trusts Zhang He's versatility for his plans and relies on him during the later parts of the Three Kingdoms period. In recent titles, he shares a loosely trusted partnership with Cao Pi and the heir refers to him by his style name. Sima Yi is fascinated with Cao Pi's abilities and generally finds him a better ruler than his father.
Sima Yi's fans are named to contrast Zhuge Liang's throughout the Dynasty Warriors series, the most obvious example being the black fan he wields as his third weapon. His fourth weapon is originally named after Qiongji, a mythical beast in legends. One of its key aspects is its hatred for just or righteous people. Should the members of an argument be confronted by the beast, it decapitates the one who is morally correct and shreds their bodies to pieces. For the unjust ones, the qiongji hunts for them and thinks fondly of them. Since one description of its appearance is a tiger with wings, Sima Yi may be designated with the beast to contrast Zhuge Liang's nickname as a dragon.
His level 11 weapon is named Suanxing, which is a name for the three-legged bird in Shan Hai Jing. Within Chinese mythology, these birds are a symbol for the sun and were once responsible for dictating the path of ten suns in the sky. When all ten suns happened to pass over the land simultaneously, the lands were set ablaze. Since the birds travel west to make the sun set, it conflicts with Sima Yi's rival, whose same ranked weapon pairs Zhuge Liang with Qinglong of the East. Alternatively, it may be a reference to Sima Yi's relationship with Wei and his gradual departure from it.
The English translations for his claws in the sixth title are accurate, but they omit the personification attached to them from their original names. Within the Asian ports, each weapon is affiliated with a character that may be used for sound or musical rhythm. In other words, his weapons are meant to invoke the imagery of people screaming in agony, as though Sima Yi were conducting a "symphony" to their suffering.
In the Asian ports of Warriors Orochi, Sima Yi personal item is Sima Fa or The Methods of the Sima, one of the seven military classics of ancient China. Sima Xing is not one of the argued authors of the work though Sima Ranju, a general of the Qi state, is among them. Whether he actually wrote the histories and theories within the documents are still unknown.
Sima Yi began his career as Secretary of Literature under Lord Cao after the pacification of the north. His first military assignment was against Zhang Lu in Hanzhong. Sima Yi’s strategies were a success and Lord Cao was greatly impressed.
After Cao Cao, and his son, Cao Pi passed away and Cao Rui stepped up to the throne, Zhuge Liang started his expeditions to the north. In 227, Meng Da attempted to defect back to Shu. After hearing this, Cao Rui sent Sima Yi to Xincheng to stop Meng Da from defecting. The battle killed Meng Da in the process and Sima Yi was given much praise. Starting from the year 228, Cao Zhen led the defense against Zhuge Liang while Sima Yi led the strategies for the battles.
In the year 230, Cao Zhen passed away and Sima Yi took command against Zhuge Liang. Also in 231, Sima Yi finally faced Zhuge Liang's armies in battle. Sima Yi was mocked by his generals during the battle for not facing Zhuge Liang's men directly in battle. Furious, Sima Yi sent his men but was defeated easily. Sima Yi didn't falter and waited for Zhuge Liang to retreat. Indeed, Zhuge Liang retreated due to lack of supplies and Zhang He was sent by Sima Yi but was killed at Mumen Trail after being ambushed by Zhuge Liang's men.
In 234, Zhuge Liang began his final expedition to the north and met Sima Yi's men at Wuzhang Plains. During this time, Zhuge Liang sent a message to Sun Quan to attack Hefei in which Sun Qun accepted. Zhuge Liang attempted to force Sima Yi out of the Wei's main camp but none of the attempts worked. Sima Yi's men were getting impatient and Sima Yi requested to Cao Rui to engage the Shu forces. In response, Cao Rui sent one of his strategists, Xin Pi, to tell them to be patient. In time Sima Yi sensed that Zhuge Liang wouldn't live long due his rival's attempts of forcing him out of the camp. Sun Quan was defeated at Hefei due to a mysterious plague causing his men to fell to illness. Wu's defeat caused Zhuge Liang stress and fell to illness in Autumn 234 and died weeks later.
Sima Yi sensed his rivals death and quickly attacked the Shu's Forces. Even though they were quickly charging to the Shu's main camp, Sima Yi felt that Zhuge Liang's death was fake and ordered his men to go back to camp and Shu retreated safely.
During the Reign of Cao Fang; Sima Yi was appointed as Prime Minister and received the Nine Dignities from Cao Fang. Sima Yi placed his sons Zhao and Shi in high positions and took away power or killed anyone who still supported the Cao Family. Also duing Fang's reign, Sima Yi started a rebellion which caused Wei's regent, Cao Shuang, to step down. Sima Yi took position as regent later on and his sons, after his death, gave high contributions to Wei including Shu's fall during Sima Zhao's reign in 263.
As regent, he quelled a rebellion led by Wang Ling assisted by Wu at Shouchun. After the long battle, Sima Yi fell ill and Sima Shi became his heir to his position.
Sima Yi died in 251 AD and was succeeded by son, Sima Shi. Fourteen years later, his Grandson, Sima Yan, usurped the throne and established the Jin Dynasty.