Detective Mara Vance stood in the rain-slicked alley of Neo-Kyoto, her cybernetic eye scanning the crimson glow of a dying neon sign. For weeks, she had chased a ghost through the city's underbelly—a thief who stole not credits, but the very rhythm of life from her clients. However, tonight was different. A new clue pulsed on her wrist display: a single red blood cell, tagged as "Oxy," had been spotted entering the heart's main artery. If she could follow it, she might win the competition against the rival detective agency and finally solve the mystery. The stakes were high, but Mara had never been one to give up.
She injected herself with a microscopic tracking drone and felt her consciousness shrink. Suddenly, she was inside the bloodstream, floating alongside Oxy, a bright red cell carrying precious oxygen. "Hold on!" Oxy shouted, as they were pulled into a powerful chamber. The heart's pump thumped like a bass drum, pushing them through a valve and into the lungs. There, Oxy exchanged carbon dioxide for fresh oxygen, and Mara realized that blood carries oxygen and nutrition to every cell in the body. However, the journey was far from over; they had to return to the heart for another round.