Treasure hunter Kaname discovers an anomalous metal artifact deep in the Amazon rainforest. The symbols etched on its surface don't match any known ancient civilization—instead, they match the 'Imperial Mark' he witnessed five years ago in North Africa. That night, Riao, an investigator from the Empire's secret agency 'Bureau of Grey,' appears before him. She doesn't coerce but persuades: the artifact is likely an activation key to an ancient weapon. The Empire has concealed its existence for 3