Adolfo was the leader of a group called Umbra which trades slaves all over the Eliora continent.
Umbra was an organization of slave traders from various kingdoms on the continent.
Its leader had long been undisclosed and remained secret but it was apparently Adolfo. He had simply pretended to be just the owner of the largest slave trading company in Crux to not catch the eyes of the Council.
And yet, Medeus itself was where the purchase usually happened since it was where nobles from various kingdoms were typically gathered.
The slave trade happened right under the nose of the Council even though most kingdoms in Eliora already condemn it.
Umbra was also the same organization Gulliver had supplied with Prudencians to be sold over the continent.
"Heh. I see. It's high time they pay the price," Ferdinand decided to crush Umbra.
Meaning, it would be catching two birds with one stone. They get to rescue a lot of Prudencians and catch the mastermind of Arabella's poisoning.