The day had begun like any other for Collins—brushed with the scent of turpentine and streaked with the vivid hues of paint smears on his fingers. He had just completed a commissioned piece—an abstract of a lion engulfed in flames—and was preparing to deliver it to the address he'd been given anonymously. He didn’t think much of it; his clients often preferred discretion.

The address led him to a secluded mansion nestled in the greenbelt of Maitama, a place only the old money dared to boast of. He drove up the driveway, uneasy, as his beat-up sedan looked wildly out of place among the sleek luxury cars parked outside. A...