The Oni's name is Han. He was the most powerful of his kind, an immortal race of demonic men that ruled over humans under the guidance of Xhu. The Oni were completely unlike any other creature that shinobi know today. To put it into perspective . . .
The land of demons was once the only inhabitable area in the world. Everything else was a wasteland, an endless sea of fog and nothingness. The air was putrid and killed any who ventured in. Only the Oni, and Xhu, could wander these lands.
When Xhu died, his dead body split apart to form the rest of the world; the nations surrounding the land of demons, the mountains, the species of animals, chakra and certain abilities. The demons, even as powerful as they are, were only a small fragment of Xhu. He was literally a God, and so knowing that, one can understand that the Oni, who were able to kill him (though with hundreds of them) are all exceptionally strong.
Your average Oni was about as strong as Kurama. Which is, well, obviously quite overwhelming. Han, the strongest of the Oni, was beyond the perception of the shinobi today. Even the greatest shinobi of history and of now would not be much, alone, versus this creature. He is of unprecedented power.
But he is dying, weakening, constantly. He seeks an answer to his decaying soul. It is a human body.
As mentioned in "The Story", Han has been nurturing a human vessel for a hundred years to open her body to his domineering. However, that vessel will only serve one greater purpose:
It would allow him to host a bijuu, a limitless source of energy that could sustain his immortal body for all time. He would be beyond what he was in his glory days, and with such capability in his hands, he would be virtually unstoppable. He could easily become the supreme figure of the human world, dominating the lesser species to his tune.
If Han can get even one bijuu then he will essentially be only stoppable by means of straight-up combat with him. It would be grave and trying to fight him would be extremely risky for anyone.
However, it is understandable that Han might not be able to obtain a bijuu before rotting away, with his weakening body and dying source of energy.
So there are three great wonders of the world that are key to his strategy:
The Tree of Life, the Great Desert Beast, and the Gedo Mazo. There were once dozens of these wonders, but Han has drained them of energy to keep his body running, and now only these three highly protected entities remain.
He will be raiding villages to obtain the energy from these wonders. He will be raising hell. He will be ruthless.
The Tree of Life resides in Kusa.
Gedo Mazo was buried beneath the Hidden Rain.
The Great Desert Beast lays next to one of Konoha's coastline cities, most people imagining it to only be a rocky hill.
Securing these objectives is extremely imperative.
Now, importantly:
Han can bring RPCs to his side. He will approach each Kage and ask them a similar question: do they believe in God, an afterlife, will they listen to a story? Each of the Kage will be in a dangerous position.
One thing that's extremely important about Han as a villain is that he is not built around plot armor and villain monologue. He is extremely ruthless. If he can find a time to strike, an ideal moment to assassinate a Kage or fight them alone, he'll take it.
Those are my ideas for his objectives and how he'll be acting. Thoughts?
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