A General idea
You know what they say sometimes a hint f what is supposed to be made is better than an explanation, so I will do a bit of a beginning, changes can be made if wanted, but this is a general idea
The world is divided, terraformed, and altered in ways that cannot be explained, but worse is that would is divided, a barrier made from a source of power unknown to the world divided the world into three, though before being made the land change and wrapped becoming three continents that hold citizens within certain forms of society, The upper class, with is in the Northern part of the world, the middle-class which is in the southwest of the world, and the lower class within the southeast of the world.
While the world became divided, it brought peace to its people, this is no normal world, you see this is known as the world of Remnant, in this world while there are human's there is another form of race that exist, and they are called Faunus, who are human's with animal-like features, they were treated poorly due to them having these kinds of features, but in a situation like this there was no choice but to make peace, and soon all enjoyed the others company...except for the upper class, who are known to be racist most of the time, and looked down on those from the lower forms of society.
In this world, there are also creatures known as Grimm, that have brought death and destruction, but when the world change they started to slowly become instinct, in a land where the grim is born, the liquid that they come from started to slowly evaporate, not only that it's counterpart a land filled with light started to lose all that as well, soon becoming nothing, leaving the land of the Grimm, but for every Grimm made, and depending on size and species the liquid they come from disappears faster and faster.
To which two beings notice immediately.
Though unknown to the populace they didn't know of a group being formed in the shadows, all except three people, and two that are close to them, who knows of this threat. As well as a being that fights what this group has created.
*Unknown Location*
Three people are in a dark room, each sitting at a desk, but no one can give a description of what they look like due to the darkness, it was as if they were giving a report due to the fact that each had an assistant that handed each of the three a clipboard.
"I will start this meeting with my report, and get the most damage out of the way." One figure spoke, leading everyone else to wince or to give off a slight alarm reaction, and seeing this made the figure sigh, before continuing. "The amount of dust that we obtain and are still good to use has decreased once more, since the sky walls appearance five years ago, the amount of just that is still good is almost fifty percent, and starting to decrease rapidly, if we are still lucky any dust we get, we might have more than a twenty-five percent chance of getting dust that can be used, but with the remnants of the White Fang still in the area stealing them, or using them as explosives, our side of the world will be unable to give anyone dust, Grimm activity is almost non-existent, but we are not making clear advancements in making electricity, everyone is arguing, and sabotaging each other that no one can make something that will help...I also concluded that the relics are slowly becoming useless and that when we run out of dust, and no more Grimm exist then they will be completely useless...meaning Atlas will fall in a year or two at worse..."
*Unknown location*
This Day could have not been any worse, first, there was a robbery, then a well-known criminal was trying to escape onto an airship that probably had an alley of said criminal, but there is also a monster that she has been told had been around all around the continent, now there was a civilian with silver eyes, with black hair that had a shade of red mixed to it, making her remember a certain student at Beacon, the only thing that was good was that the monster was attacking the criminal's as well, but any sort of dust or semblances, or anything that the criminals or the girl threw at it had no effect, it was honestly starting to seem hopeless.
VORTEX FINISH!
With that announcement being called out, everyone tried to look for the source, until something caught the Silver eyed girl's attention, it was something covered in red and blue energy, which crashed into the airship, causing massive damage, and then hitting the creature, who went flying from the attack, once it was all over the figure stood up, causing everyone who could see that the figure was a man, even the ones from the airship that barely could leave.
The man was clad in blue and red metal armor over a black bodysuit, his left leg was clad in red metal like armor with a strange white spring wrapped around his shin while his right leg was clad in blue metal like armor, and his foot looked to be a tank's caterpillar track. His left arm and shoulder were protected by the blue metal with a double protrusion of a blue tank's muzzle and a red 'rabbit ear' pointed outwards past his left shoulder; his right arm and shoulder were clad in the red metal, as opposed to his blue counterpart mask was a mix of red and blue metal; his visors were a red rabbit's head with the ears pointing diagonally left and a blue tank that pointed diagonally right.
There was also the fact of the strange belt attached to his waist, if that is what you could call it, there was a device that was pure black with a few dashes of red, with a handle that your use to turn, and a handle that you wrap your hand so that you can use the other handle with no problem, there was designs of gears, and a clear circle, that honestly made no sense to the silver eye girl, but something that really caught her attention was two bottles attached to the device, one red, another blue, just like his armor.
The man-made no signs of acknowledging them, but he did pull out a bottle and pointed it at the monster, which did something strange, it was as if the bottle was absorbing the energy of the monster, and transforming it into a human, a real human, shocking everyone, and with that done, the man lifted the bottle and examine it.
*Unknown location*
*BAM! DING!*
A figure jumped out of a bed, startled yet excited, the man run towards the sound and picked up a bottle, from a machine that looked like a microwave, that was attached to an even larger machine.
The man now that we have a good look at him was wearing black cargo pants with multiple pockets, black and white sneakers, a burnt orange hoodie, with a black trench coat, but an off thing was that he was wearing a black mask that covered the lower part of his face, he had blue eyes that looked as pure as the sky, and shaggy blond hair that had a perfect mix of red to it, though it didn't look natural.
The man was looking at the bottle with awe before he made his eyes form an eye smile.
"I wonder what the best match to this is?"
And that is it, a general idea of what a Naruto, Kamen rider Build, and Rwby crossover should ideally be like, a mix of something from all three, hope you enjoy it, and I will see you all next time.
