I was considering the possibility of Imu being an orochi type character, but it doesn’t make sense.
Imu is the opposite of Orochi. While orochi is something of a figurehead, with Kaido pulling the strings, Imu is in the shadows with the world believing the gorosei are the rulers of the world.
If Imu isn’t strong then there’s no way he could rule the world from the shadows. Dude probably killed Joyboy, meaning he’s likely top 1.