The Oni is a race in the world. Oni or Onis are a species of large human-like beings having rough like appearance. They were once a large and thriving species in the world until as of a few hundred years, where the World Government had begun for unknown reasons began to hunt them down, quickly dwindling their numbers. Since then they have isolated themselves until recently where their home island of Fuji had officially aligned themselves with the Yonko Esposito Dante.
The oni are large humanoid beings, typically built much larger than the average human, most having much stockier build. Their most distinguishing physical feature are their horn protrusions coming from their forehead. Some have one while others have two, with different oni having different shaped and sizes horns. Though if it weren't for their horns or primal forms, most would simply confuse them for humans, something they're not fans of.
When some enter their "primal form", their bodies are also usually colored with less human and more Fishman-like hues.
The Oni skin is extremely durable, their bodies being reinforced by the high amount of natural muscle they posses in their bodies from birth. Conventional weapons such as guns, swords and in some cases even canons struggle to even harm the more seasoned and trained Oni. Even after being blasted with dozens of mortars from Marines, a well-trained Oni will be able to stand almost unfazed from the bombardment and continue the battle.
This natural durability also ties into their monstrous stamina, capable of fighting for hours on end, some even days. This comes from their tribal like lifestyle with the different tribes having their own methods of training. For example a clan can run up to two hundred miles in distance to gather or find new resources, while others shatter boulders for taking down much larger prey. Some are even known for scaling mountains with large boulders in the efforts of only becoming stronger both their durability and their endurance.
Being a more violent and warrior like species, the members of the Oni race are born with inhuman levels of natural strength from birth thank to their natural biology. Much like the minks they are capable of fighting and engaging foes from an early age well into their golden years. Able to lift and crush massive, thick boulders from a young age as part of their culture's training. They're known as some of the most dangerous predators in all of the seas, typically found at the top of the food chain of any island they would inhabit. Beings such as Giant Wolves or Lions have been seen wrestled down by the likes of Oni.
Among the Oni, there are some capable of shapeshifting, taking a much more human-like appearance. Their skin turning from their natural color to a one much more human, even becoming shorter and have a much less muscular stature. Typically they use this form to infiltrate human cities without alarming others of their presence, especially those affiliated with the World Government.
Though in reality this human like form is actually compressing the Oni attributes, resulting in even greater feats of physical capabilities.
The biggest natural weakness the Oni suffer from is their large calorie intake. They require to eat large amounts of food to feed their abnormally large and physically towering bodies. They need to both hunt large animals yet also learn to farm them to prevent the total extinction of their resources. If they don't meet their diet requirements, their body will quickly suffer from nausea reminiscent of motion sickness and dramatic loss of physical abilities.
Roughly five hundred years ago the Oni race lived as mighty warriors and hunters, roaming, ravaging the sea of the Grand Line, North Blue and West Blue. Most being seen as monsters for their violent actions, burning villages, stealing from the natives of islands.
Their home and the native island was called Kira, an island found actually in the heart of the New World, which allowed them to have a wide range of options to go about things such as attacking nearby islands or even extending them through the two surrounding calm belts to reach the two neighboring blues.