Fujiwara no Michinaga dominates Heian-kyō's aristocracy and wields considerable political power, his family a ruling force of the era. He expresses a longing for a purely noble existence yet accepts his duty to oversee the capital. Michinaga develops an attachment to the Makai Priest Seimei, who consistently evades his approaches. Seeking to bolster his regional control, he desires to command a powerful Makai Knight, specifically the Golden Knight.

A significant revelation exposes Ashiya Dōman, a fallen Onmyōji, as Michinaga's infant brother, cast away for unknown reasons. Michinaga offers reconciliation, but Dōman refuses, consumed by resentment. Michinaga typically clings to emotional control, remaining composed during palace attacks and the Crimson Moon phenomenon. He explicitly vows never to become a Horror and draws philosophical parallels, such as linking Raikou and Dōman through concepts like yin and yang.

His character unravels during the ancient cherry blossom tree Horror crisis in *The Fleeting Cherry Blossom*. This Horror is unleashed by Tokimaru and Akira, descendants of Duke Kan (Sugawara-no-Michizane of the Hajimi clan), seeking vengeance for Michinaga's role in exiling their ancestor on false treason charges – an act for which he shows no remorse. Confronted by the Horror's curse, Michinaga abandons the populace, denying commoners sanctuary within the Light Palace and deceiving the public. He further frames Minamoto no Yorinobu for stealing the magic book sustaining the palace's protective barrier and demands Yorinobu's execution.

As the Horror's curse spreads, Michinaga descends into madness, believing himself invulnerable due to his retainer Akimitsu and callously welcoming others' deaths. Following the Horror's defeat by Raikou, Seimei, Kintoki, and Yasusuke, Michinaga faces consequences. He is stripped of his titles and arrested for his callous disregard for the capital's inhabitants' safety.