Yozo Oba inhabits a dystopian future where nanomachines under the S.H.E.L.L. system have conquered disease and death, fracturing society into privileged elites in the "Inside" and the marginalized in the "Outside." Drifting through the squalor of the slums, he numbs his purposeless existence with substance abuse, haunted by recurring nightmares that whisper of deeper psychological scars. His life shifts when a reckless raid into the "Inside" with a biker gang thrusts him into the "Human Lost" phenomenon—mutations consuming those severed from S.H.E.L.L. Amidst the chaos, Yozo awakens latent abilities to manipulate these grotesque transformations and the "civilization birthing curve," a predictive model dictating societal futures. This power draws him into a clandestine war waged by other "applicants": Yoshiko Hiiragi, whose steadfast empathy challenges his detachment, and Masao Horiki, an anarchist weaponizing rebellion against systemic oppression.

Yozo’s fractured past, marked by undefined familial trauma, fuels his oscillation between apathy and duty as he confronts the regime’s injustices. Positioned as a reluctant catalyst, his journey grapples with humanity’s entanglement with immortality and control. While his evolution from observer to insurgent underscores themes of existential purpose and inequality, the narrative’s rapid pacing often sidelines his emotional depth, prioritizing clashes of ideology—Yoshiko’s preservation against Masao’s nihilism—over gradual personal transformation. Yet through these collisions, Yozo’s struggle mirrors the broader conflict: reconciling individual scars with the violent rebirth of civilization itself.