Aide wanders the country of Orthozes as an amnesiac, retaining only his name. Despite exceptional combat prowess, his failing memory forces him to document experiences in a journal. His physical resemblance to Fract—ruler of neighboring Bjor—ignites escalating conflict.

Joining Orthozes' mercenary resistance, Aide allies with Mara, a Crimson Knight haunted by Bjor's slaughter of her parents, and Dino, a demon warrior fighting to sustain his daughter after similar Bjor aggression. Aide seeks purpose and identity through this shared trauma.

War's progression exposes Aide's ties to Fract and the enigmatic entity Mugen. Their identical appearances are revealed as Mugen's doing during a climactic confrontation, where Aide uncovers his origins and connection to Fract. This revelation twists Aide's role in the conflict, partially redeeming Fract.

A post-credits scene casts ambiguity over Aide's actions and legacy, implying his path diverges from traditional heroism. His journey navigates identity, wartime morality, and violence's cyclical nature.