Ayato Kamina, Hiro Shimono, and his classmate Reika Mishima are a young couple in middle school, still feeling the awkwardness of first love. Their routine world is shattered when visitors from an alternate dimension, the Mu, arrive and Tokyo is swallowed by a colossal hemispherical barrier—the Absolute Barrier—that looks like a moving planet and seals off the city, splitting life into two realities: one inside and one outside. With the barrier in place, Ayato and Reika are torn apart and must navigate a suddenly fractured future.
Three years pass inside the barrier, and Ayato has grown into a high school student who has been told the outside world has been erased. Time moves differently inside, and memories of Reika feel elusive, almost like echoes from another life. Then invaders from outside attack again, and Tokyo erupts in fresh war. A woman named Haruka Shitou appears, guiding Ayato and promising to reveal the truth about the world they inhabit.
> I’ll tell you the truth.
The promise behind Haruka’s appearance unfolds into a far deeper secret: she is the person Ayato once loved, Haruka Mishima, now separated by years and circumstances. The barrier’s time manipulation has been part of a larger scheme, tied to Maya Kamina, Ayato’s mother, who is revealed as the Mu’s leader. Ayato is introduced as the tuner of time, a figure who could reshape a world torn between Mu and Earth and whose awakening holds the key to humanity’s fate.
As Ayato awakens, he is drawn to the immense war machine RahXephon, a being that seems to hold the solution to the crisis. He boards RahXephon and, with the Mu’s weapon Dolem, defeats the threat and escapes Tokyo with Haruka. Haruka remains a constant support, though she cannot reveal her true identity yet, staying by his side as they run from the collapsing city.
But a far harsher fate awaits. When Ayato achieves true awakening and becomes one with RahXephon, the world teeters on the brink of destruction. To spare both Ayato and the planet, Haruka must make an almost unbearable choice: kill the man she has found again in order to save everyone else. Her decision tests the boundaries between love and duty, between memory and sacrifice, and asks whether a single act of courage can fix a broken world.
The story delves into how memory and identity shape desperate choices in a cosmos where time itself can be tuned. The bond between Ayato and Haruka becomes the anchor of a sprawling conflict between two civilizations—Mu and Earth—as they push against fate, longing for reunion while confronted with the cost of awakening. Maya Kamina’s shadowy influence lingers, casting a calculating calm over events as Ayato confronts the responsibilities and consequences of a power that could remake the world.
In the end, the film presents a meditation on love, power, and the price of knowledge, asking whether a future built on memory, reconciliation, and sacrifice can ever be saved from the damage of a single, world-altering awakening.
