Each One Piece fan has already met the character called “Killer”: he’s a member of the Kidd Pirates and also one of the Supernovas, who are the rookie pirates who have a bounty higher than 100.000.000 Berry.
Despite this information and despite the fact that we have already seen him fighting, no one has already understood his role in One Piece, but we can be sure that Oda never creates important characters to make them irrelevant. At this point, who is Killer? How does he look like? Where is he from? And why does he wear a mask?
In order to answer all these questions, today I’m going to introduce you my theory about Killer’s real identity.
To begin with, in chapter 641 we see an image in which there is Crocus, a former Roger Pirates member, who is drinking saké along with a person who looks like Oden Kozuki, but we know that Oden had been already executed by the Yonko Kaido, so who is he? Well, since the Kozuki family was a very powerful family, we can’t think that it only had 3 members (Oden, Oden’s wife and Momonosuke); for this reason, I think that Oden had at least an elder brother and in that image maybe Crocus is talking to him about Oden.
In addition, if you pay attention to the image, Oden’s brother’s hair is very similar to Killer’s ones, so, in my opinion, I think that, as a kid, Oden’s brother wanted to become a pirate as his older brother did before him, so he left Wano but he was captured and became a Celestial Dragons’ slave. We know that the Celestial Dragons are used to put a mark on their slaves’ bodies, like they did on Boa Hancock’s back.
For this reason, I’m strongly convinced that Oden’s brother received Celestial Dragons’ mark on his face; then he achieved escaping from them, but he couldn’t go back to Wano because showing that a member of the Kozuki family had been a slave would have caused in him an immense sense of shame, so he started to wear a mask to hide the only symbol which could prove his slavery experience and he went on trying to become a famous pirate; in the end, Killer has been able to join the Kidd Pirates, so he accomplished his aim and, thanks to it, he started a new life.
Moreover, since he originally comes from Wano and since after the Big Mom arc we will probably see the Wano arc, maybe Killer will be one of the characters who will help the Mugiwaras, like, for example, the Mink Tribe is doing ad Marco The Phoenix is supposed to do