In chapter 954 the Numbers are first mentioned and they are going to show up for the Fire Festival.
The Numbers are comparable in size to giants, utterly dwarfing humans and longarms like Scratchmen Apoo. They all possess two horns on their head, much like Kaido, and two of them carry a spiked club similar to Kaido’s kanabō, thus giving them traits similar to those of the legendary oni.
Two of them have been shown with very sharp teeth. Their physical constitutions vary greatly, with some being taller and slimmer while others are shorter and rounder. One member has a notably long neck.
According to Queen, every member of the Numbers has a drinking problem.
A child from Hakumai told another child that they would be eaten by the Numbers if spotted, but it is unknown whether that is the truth or a myth. Likewise, he also said that they were from Onigashima, but it is unclear whether he meant that they were native beings of Onigashima or that they were members of the Beasts Pirates who are situated in Onigashima, hence stating that they were from there.
So the Numbers seems to be a species we haven’t seen before or atleast not of a species we know of. Or do we? I have 2 theories:
1: The Numbers are the same species as Oars
The Numbers are clearly tall. They have a demon-like appearance. We know that Moria most likely have been in Wano and there maybe he found Oars’ body.
2: Kaido is the same species as The Numbers
This one is a little weird. But what if Kaido came to Wano because his race (The Numbers) were hunted by World Government and then he found Wano, a country that got almost no contact with the rest of the world. He then came with The Numbers as their leader, and they fought with Kaido to dethrone Oden. Queen also said that The Numbers all have a drinking problems and so do Kaido (and it would explain the horns).
*Theory by XxNOTMYFAULTxX