Ichiro Sato lived for the hum of servers. At twenty-four he’d built a small but formidable reputation as a backend engineer who could find a needle of latency in a haystack of distributed systems. He worked nights, fueled by black coffee and the thrill of bringing order to chaos. On the surface his life was ordinary; beneath it, he was always chasing a ghost — a nagging memory of a promise he couldn’t fully recall.