Description
Sima Yi Destiny Gundam serves as a primary antagonist throughout the SD Gundam World series. He shares an academic history with Zhuge Liang Freedom Gundam, having studied under the same scientist, yet maintains ambiguous loyalties toward his former peer. After plunging Kingdom World into chaos and suffering defeat against Liu Bei Unicorn Gundam and Zhuge Liang, Sima Yi vanished from public sight.

He operates as an evil mastermind, secretly scheming to endanger multiple worlds from the shadows. Within Musha World, he adopts the disguised identity of Rikyu Gundam, masquerading as a tea ceremony master to manipulate events covertly. His machinations extend beyond Kingdom World; he plays a pivotal role in forging the series' central threat by forcibly fusing the three humanoid guardians—Wukong Impulse Gundam, Sha Wujing Silhouette, and Zhu Bajie Silhouette—into a single entity. This fusion involved implanting false memories in Wukong, making him believe he murdered his companions, thereby exploiting guilt through psychological manipulation.

Sima Yi later allies with Qiongqi, a being seeking the annihilation of worlds corrupted by human desires. Together, they plot to merge all realities into the artificial planet Dark Star, intending to reset existence under their control. During the climax, he transforms into "Sima Yi Destiny Gundam Dark Star," merging with the Dark Star to become a colossal manifestation of their destructive ambition. His ultimate objective is the eradication of all human life, which he views as inherently flawed.

Following a decisive battle where Wukong Impulse Gundam achieves a new form, Sima Yi is defeated alongside Qiongqi. The Dark Star is destroyed, leaving his ultimate fate unclear.