In a distant era of perpetual conflict between the Union and Deague factions, Sara Werec, a young cadet at the Grapera Space Armed Soldier Academy, aspires to become a skilled Reasoner pilot operating the powerful Strain machines. Separated from her brother Ralph, who embarked on a mission light-years away, Sara's determination to reunite with him intensifies. When her world comes under sudden attack by Deague forces, she discovers her brother among the invaders, leading to a confrontation that leaves her Strain's control system compromised. Now, Sara must unravel the mysteries surrounding her family's past and navigate the blurred lines of loyalty and betrayal in a war-torn universe.