Kaido was a true unkillable nuisance. No matter where he was locked up, he always caused trouble, leaving the Marines with a massive headache over how to deal with him. He had been imprisoned in Impel Down more than once, but every time, they eventually had to let him go and send him back to wreak havoc in the New World.
The reason they did not simply release him outright, aside from preserving the Marines' authority, was that releasing him after imprisoning him in Impel Down kept him in line for longer. Kaido would not come looking for trouble with the Marines so often.
There were many powerful people in the Marines, and quite a few could beat Kaido senseless now, but no one could kill him. He was a huge pain!
After secretly observing where Kaido was being held, Carlos returned to Kamui Space for dinner. He disguised himself and quietly waited for the dead of night.
At two in the morning, Carlos used Kamui to silently infiltrate a specially made gigantic cell on the fourth floor, the Blazing Hell. A large number of Impel Down soldiers stood guard outside, all of them wide awake with their eyes opened wide.
It was not that the soldiers were exceptionally devoted and had no intention of dozing off. Beast Kaido's snoring was simply too loud, like muffled thunder. They could not sleep at all; the noise was unbearable.
Wearing a Spiral mask and a Black-and-red cloud outfit, Carlos stood silently before Kaido.
The moment Carlos stepped out of the spatial vortex and landed, Kaido, who had been sleeping soundly and snoring loud enough to shake the heavens, suddenly opened his eyes. His gaze locked onto Carlos at once. He looked puzzled, but said nothing.
Amaterasu!
Carlos did not speak either.