Imu's existence is kept a secret within the World Government to maintain the illusion that there is no singular ruler of the world. This level of secrecy is so intense that even the Five Elders, who are publicly considered the highest authorities of the World Government, bow down to Imu and serve their every whim. The secrecy around Imu's existence allows them to wield immense power and control while remaining undetected, making them one of the primary overarching antagonists in One Piece.