Just a small speculation, that might twist certain things within the World Government, in the end it is pure speculation, but for me a whole new idea. I hope some people acknowledge this as an idea!
I wonder if Imu-sama really is directly above the Gorosei.
To be direct, I wonder who that person to the left is. He seems to have access to the “Room of Flowers”, which seems to be a private room of Imu-sama.
In order to talk to Imu-sama, the Gorosei had to bow down infront of the throne. Also Imu-sama held a much higher position there.
Back to the guy to the left of Imu-sama, he is bowing down, but Imu-sama shows him his back.
This could mean that this person could be Imu-samas back up and hence a kind of “Right hand man”. Managing such a powerhouse as the World Government, might give you the need of a person to have, which delivers you the most direct information and executes your most personal orders.
A kind of consultant? A kind of buttler? Yes someone chosen with skills and trust over decades probably. A person most loyal to Imu. A person whose loyality exceeds the loyalty of the Gorosei.
If we have a look at the structure of the Charlotte family, we had Katakuri as person who sides Big Mom, due to his powers. The others had “Commander” and “Officer” status.
The Five Elders kneeing before Imu-sama could mean that they as a group fulfill the role of “Commanders”, so I think that Imu-sama also could have an “Ace” or “Right-hand”.
*Theory by Rej