There were three grades of cities in Nvidia.
Grade C, the lowest grade, was defined by lesser technological infrastructure and poorly defined system security against the Nakros attacks.
One of those cities was Mechron, from which he had just departed.
Then there was Grade B, a step up from Grade C, with better amenities and better defense systems against the Nakros.
Elloscious City, where he came from, was an example of a Grade B city.
Finally, there were the prestigious Grade A Cities.
The absolute peak of advancement on Nvidia.
Even though there were about thirty-six cities in Nvidia, there were only three cities that could take the badge of being Grade A.
They were cities with the lowest invasion rate from Nakros and the best technological advancement there was.
But even then, these cities were not fully free from Nakros invasion.
One of the cities had been invaded twice, and another once.
But there was one city.
A city that no Nakros had ever stepped into.
A city impossible to penetrate and humanity's strongest hold.
It was called the City of X!
And right now, Ryuk was standing before it, overseeing its entirety.
It created a feeling so surreal it could never be fully put into words.
He could only stand there silently, but only for a moment, as The Boss snapped his fingers and out came something from the vehicles.
They were hoverboards, but with no tires.
The Boss stood on one of them, leaving one remaining.
"I'll give you a quick tour around," he said, and Ryuk stood atop the hoverboard.
It was his first time, but he understood the mechanic.
The hoverboard was a technology that reacted in microseconds to the body's micro-muscular needs.
If a person wants to move forward, slight muscle changes occur, and the hoverboard detects this immediately to move in that direction.
It is also equipped with self-balancing technology that makes falling nearly impossible.
The Boss rose higher into the sky, and Ryuk held his head upward as the hoverboard also followed up, and soon they both zoomed forward through the sky, rising farther above most vehicles.
_______
"X City doesn't offer citizenship passes, nor does it even allow the entrance of those from other cities," The Boss began as they flew above the city.
"The only way to get in is to have someone already in."
"And even then, there is a level that must be reached before one is allowed to bring in an outsider."
"And the outsider has a limited time they could remain within before they would need to return to their cities."
"I guess that's why some call it the Ex City, with the Ex being Exclusive," Everlearn said and The Boss chuckled.
"Perhaps."
"But there's an important reason why this is, and that is to maintain the Nvidian potential of X inhabitants," he said, something that Everlearn didn't fully understand.
"Nvidian potential?"
"Yes."
"Nvidian potential is the purest gene of potential of the realest Nvidians, and this potential actually is the source of the Fusion Affinity potential," he explained.
"The lowest affinity potential recorded in X City is C-grade," he said, blowing Ryuk's mind.
"C-grade!?"
"Look below you," The Boss said as Ryuk turned beneath him.
"Every single person you see has at least a potential C-grade fusion affinity, something that is one of the highest peaks of even some B-grade cities," he explained, and it numbed Ryuk.
"The average affinity potential here is B, and A is the one that turns people's necks."
"But we also have close to a 100 S-grades recorded."
"S-grade!? I thought that was a myth," he said, and The Boss shook his head.
"Ash recommended you, right?" he asked, and Ryuk nodded.
"Then, you've already met with an S-grade Corer," he said, making a glint cross through Everlearn's eyes.
'Boss Ash has S-grade potential!?'
Now it made more sense why she was so powerful.
"Refusing entrance from other cities, in a way, preserves this talent that people in X City have."
"It is a complex process, but at least you should have an inkling as to why X limits entrance for most people," he said, and Ryuk nodded.
For them to maintain such talented potential, there definitely had to be something they were doing that most other cities weren't.
And truly, making entrance incredibly hard was definitely something that made them different from most cities, which had more lax entry requirements.
"And even though X inhabitants all look similar and no different from each other, there's an important hierarchy that makes some X Nvidians far superior to others," he explained, and Ryuk's brow furrowed.
"But that's not something you have to worry about," he added.
"The X mark you have on your neck isn't just a sign of citizenship. It is an X Guardian Mark."
"X-Guardian?"
"You have met with two Guardians now, Everlearn: Ash and Dumbledore," The Boss said, and Everlearn nodded in understanding.
"What would you say is one thing peculiar about them?"
"Something you find special, yet the same in both?" he asked, and Everlearn didn't need to spend even a second more in thought on the question before he responded.
"They're efficient," he said, and the Boss smiled.
"Efficient? In what way?"
"Boss Ash is a good fighter. The strongest I have ever seen."
"And while I doubted Dumbledore's capability initially, when we got attacked, he was so good that I never even saw the ones attacking before they all were destroyed," he mused.
"They're efficient. Incredibly so," he muttered, but a bit downcast.
"Believe me, Everlearn, Ash and Dumbledore weren't born like that," The Boss said, as Ryuk turned to him.
"They went through years of training to become X Guardians."
"You have become an X Guardian due to Ash's recommendation, but as you may already know, you're still far from their level," he said, and Everlearn didn't argue that.
He was nothing compared to them.
"That is why you will have to start like Ash and Dumbledore did."
"They went through training to get the mark, but you already got the mark."
"All that is needed now is to undergo the training they did."
"I understand," he said.
"And speaking of training," he said, and Ryuk looked forward, finding themselves having arrived before it:
The Core Tower in X City.
"This is X Guard Academy!"