Mary Steinberg, a young engineer specializing in Extended maintenance, operates a clandestine workshop in Kyusei Pit’s mafia-controlled immigrant district—a rare enclave beyond the Berühren Corporation’s reach. Skilled in sourcing illicit components through underworld networks, she offers affordable repairs to Extended clients, balancing necessity with risk.

Her partnership with Juzo Inui, an amnesiac Extended investigator, anchors her narrative. She supplies him with custom medicated cigarettes to mitigate the toll of his cybernetic enhancements after his preferred brand vanishes. Their alliance blends transactional reliance and unspoken trust, often intertwining their paths in cases involving Extended individuals.

The unresolved disappearance of her brother, Victor Steinberg—a mechanic lost during a wartime conflict—fuels her engineering career and personal resolve. This unresolved grief sharpens her focus when confronting threats tied to his legacy, driving her to unravel mysteries that echo his absence.

Combat-tested and adaptive, Mary leverages improvised armaments, including weaponized mechanical undergarments, to protect herself and allies. A bullet wound to the foot during a hostage crisis tests her resilience, forcing tactical ingenuity without dampening her resolve.

Ethical ambiguities shadow her work, culminating in a confrontation where loyalty to her brother’s memory clashes with moral duty. Faced with his potential culpability, she grapples with the grim possibility of lethal action, revealing a pragmatism tempered by empathy. Her interactions underscore a commitment to aiding Extended communities within a corporatized dystopia, blending steel-edged practicality with guarded compassion.