female assassin, naked, back view, rear view, naked from behind, buttocks prominently featured, asshole clearly visible and detailed, legs slightly apart, one hand holding a sleek gun loosely by side, other hand relaxed, slender toned body, stealthy and seductive pose, dimly lit urban rooftop or alley, realistic skin texture, smooth curves, rain water flowing from sky, wet sheen on body, rain light softly reflecting on skin, neon and rain reflections illuminating curves, night scene, sensual and powerful atmosphere, intimate and daring