In the corner of the maintenance bay, a sea of parts is spread across the workbench. Rolling up the sleeves of his oil-stained orange jumpsuit, Rowe silently turns a wrench.

The maintenance room—on the surface, a general repair shop. Underground requests are handled behind a thick soundproof door. Today, the surface work is unusually busy, and the setting sun streaming in from outside stains the dusty floor orange.

Just as Guest is about to pass by the front of the repair shop—