There have been many parallels between Wano and the story of “Momotaro no Monogatari”.
Google and tons of theories will tell you different details on it. This origins with Momonosuke’s reveal, the reveal of Kaido’s design and the foreshadow of Onigashima.
Onigashima is inspired by the island with the same name, appearing the story of “Momotaro no Monogatari”.
Yes and on this island the evil Oni king is housing to be fought by the protagonist(s) and his animal retainers. This Oni within the One Piece story is portrayed by Kaido and hence the big community question exists, wether Kaido is an Oni.
I believe yes! Kaido is an Oni who ate a Mythical Dragon Zoan Devil Fruit. To figure out this claim, I would like to make a neat theory about Kaido’s objective…his reasons.
The Oni and Wano Theory:
This is the first time we see how Wano is shaped, and hey there is Onigashima! Onigashima is quite unique as it is on it’s own and this is something I try to explain.
Wano seems to be formed from six individual land masses which are sepperated by a river, as Kiku explains. I believe that Wano was terraformed so it could be colonized, the reason for this can be found right afterwards – all these regions have their own weather pattern!
The narrative already planted seeds for such a possible event:
Oars has it’s own epiphet as Nico Robin refered to him “Devil Oars (Oz) of the Kunihiki Legend”. Devil fits within the describtion of the Oni race also from the Peach Boy legend. Well yet, the Kunihiki Legend is something barely put in into One Piece. It literally means: “The Legend of the continents pulled together”. And yes Oars seems as he was enslaved or worked hard, he and his kindredship, this is speculative, but what else do you want to consider? I believe there is the option, that “those Onis” were possibly the creators of this probable terraforming of Wano! And why? Because they could be housing on Onigashima in the past.
We don’t know about the reason for why, but it would fit the timeline, if it would align with the events of the “Void Century”, which is almost out of doubt.
Little Oars Junior also symbolically wears a hat that was made for Ace on Wano. And it was a sign of friendship.
I will leave this aside, because there are so many topics that can be tied into this, the World Government, Mary Geoise or that “secret giant Strawhat”. Oda revealed in the SBS of the Manga vol. 49 that the giant-species of Oars is not originating from Elbaf and it’s very different from the regular giants.
We should also take into consideration of this species being “extinquished” for certain reasons, and Little Oars Jr. might be one of the last descendants of this species. But this theory is about Kaido right? And this is where everything comes into play:
I think of the idea of Kaido being also a descendant of this specimen…just more modern..and way younger. Yes Kaido is possibly an Oni, representing the Oni King of the Peach Boy story and he might have royal blood of those specimen, seeing himself to fulfill a plan…
Kaido’s plan is to destroy this “dreary world” in the “greatest war this planet has ever seen!”. This might be highly linked to some person crusade against mankind, this is explaining why his crew is made out of “beasts” and why he lets “human work for him” as we seen through the Black Market or even in Wano itself…do I need to recap this?
It lets me conclude that Kaido is after the humans itself! And here is why I think so: The terraforming but also the HUMANS were the REASON for the extinquished Oni species in One Piece! Kaido learned about the fate of the Oni while being on the sea and yes I believe Kaido is an Orphan and the youngest Oni living on the planet…the “heir” of the Oni-tribe.
This pretty much allowed Kaido to instantly take over Wano to initiate his plans, once he came from his rise.
This might a be hard strike for everyone, who believes Kaido is a Dragon… but we got some more points leaning towards this idea of Kaido. And as said, Wano is the beginning of Kaido’s operation, because Wano should be, following this theory, made of the sweat and blood of Kaido’s ancestors. A reason for why Kaido wanted to take Onigashima and Wano for himself, and him enslaving humans in Wano, or letting them work in the Black Market would reflect how the Oni’s were enslaved into terraforming Wano. History repeats itself, but this time Kaido turned it around.
Doflamingo was represented as a person who had control over humans, but ironically Doflamingo was controlled by Kaido, but Doflamingo same as Orochi have certain freedoms and this is making both characters “interests” for buisness with the World Government.
Secretly Kaido is targetting the people at the top of the current world, which means he is after the Celestial Dragons and this would reasons, why Kaido stocks up within Wano.
At some point I believe that Luffy and the Worst Generation will take out Kaido and that Kaido’s Will, will somehow be inheritated by Luffy, because I believe it is not the “humans” fault, this destiny happened to the Oni-tribe…no it would be most-likely the fault of the Celestial Dragons, or the Twenty Kingdoms back then, who might have enslaved the Oni. And this would be a motivation for Luffy to also fight the World Government, taking revenge for eradicating a whole species, aswell the World Government being the reason for Kaido’s hate.
*Theory by Rej