"Tsuru ga Mau Yoru ni" is a historical fantasy anime set in Japan's Heian period, blending supernatural elements with political intrigue. The narrative centers around Fujiwara no Michinaga, a real historical figure who rose to prominence as a powerful regent, and his interactions with a mysterious crane maiden named Tsuru. The story begins with Michinaga encountering Tsuru, who possesses otherworldly beauty and abilities, during a time of political unrest. Their meeting sets off a chain of events that intertwines human ambition with the mystical world.

Tsuru, revealed to be a celestial being, becomes entangled in Michinaga's quest for power. Her presence attracts the attention of both human adversaries and supernatural entities, creating a delicate balance between the mortal and spiritual realms. As Michinaga navigates the treacherous court politics of the Heian era, Tsuru's powers and her connection to the heavens become pivotal in shaping his destiny. The narrative explores themes of loyalty, ambition, and the consequences of wielding power, as Michinaga's rise to dominance is both aided and complicated by Tsuru's influence.

The series delves into the complexities of the Heian court, depicting the intricate relationships between nobles, warriors, and spiritual forces. Michinaga's character is portrayed as a shrewd and ambitious leader, driven by a desire to secure his family's legacy. Tsuru, on the other hand, embodies a sense of ethereal grace and mystery, her motivations often ambiguous as she oscillates between aiding Michinaga and grappling with her own celestial duties. Supporting characters, including rival nobles and supernatural beings, add depth to the story, highlighting the tension between human desires and the forces that govern the natural and spiritual worlds.

The plot unfolds through a series of political maneuvers, supernatural encounters, and personal conflicts, culminating in a climactic confrontation that tests the limits of Michinaga's ambition and Tsuru's loyalty. The anime weaves together historical events with fantastical elements, creating a rich tapestry that captures the essence of the Heian period while exploring timeless themes of power, sacrifice, and the interplay between the mortal and divine.