After the catastrophic event known as 'The Burst' unleashes a relentless and self-replicating entity called 'Matter' from a Japanese research facility in 2035, Aiko Tachibana finds herself living under constant medical observation following her rescue from this enigmatic substance. Engaged in the simple act of crafting paper planes to while away her recovery time, Aiko's tranquility is disrupted when a new student, Yuuya Kanzaki, transfers to her school and starts unraveling the mysteries surrounding her seemingly unscathed body. As Yuuya hints at hidden truths and a pivotal role Aiko plays in halting The Burst, they must navigate a web of factions vying for control over her. Together, they venture into the perilous heart of the infected Kurobe Gorge, racing against time and adversaries to confront the amorphous Matter, a fluid enemy with insidious intent, before the conspiracy tightens its grip around them.