Lin Yue, an ordinary company employee, has a secret crush on Gu Yunshen, a star at a partner company. But an accident sends her hurtling through time to a future a hundred years away.
Here, humanity relies on armor called "Heart Armor" to fight temporal erosion. The one capable of awakening the strongest armor, the "Armor of Chronology," is none other than Gu Yunshen, a hero who died long ago according to the history books.
To get home and uncover the truth behind the hero's fall, Lin Yue approaches the cold name from the future textbooks under the guise of a "historical researcher." But she discovers that the Gu Yunshen before her is kind and powerful, yet utterly impervious to love.
"Love is a weakness. It can bring you to ruin," he insists.
Lin Yue quietly protects him, using the warmth she brought from the past to slowly melt his frozen heart. When the world-ending crisis arrives, Gu Yunshen finally breaks the taboo for her, and his armor shines with a light never seen before.
But that light also reveals a cruel truth: the hero's sacrifice was the very starting point of her journey through time. Does saving the world mean losing him forever?
