やがて黒幕へと至る最適解 (Associated Names)

A young man named Kurtz pledges unwavering loyalty to Artesia, the fallen head of a ducal family. Upon discovering that Artesia’s death was orchestrated by the six great ducal houses that secretly rule the world, Kurtz spends ten years preparing before returning to the past. Now a 10-year-old orphan, Kurtz uses his knowledge of the…