“What are you up to nowadays?” Asked Adam as the flying shuttle took the air. “Lucifer, we are dropping Miles first, please.” He also notified his wristwatch.

“Besides hunting and training, nothing much.” Miles shrugged.

“How are your botany studies?” Adam asked as he looked at Miles with expecting eyes.

“I actually stopped studying them ever since I left the house.” Miles said, then added. “Sorry, Uncle.”

“It is fine. But as I said when you first came to me for Strengthening Serum— you will not be able to use them when you catch up with us.” Adam said then informed, “Look kid, we rest of humanity use serums a rank behind. Meaning, when we are in Form-Rank, we use Grace-Rank serums. Same will continue no matter what, as we are physically weak.

But you are different. Your journey started with Grace-Rank, low-tier serum, and your strength will go parallel to the serum you use. You get it?”

“It means, when I catch you at Crown-Rank, you all will be using Devote-Rank serums, while I will require a Crown-Rank one. But since no one beside me ever needed it, and there won’t be required materials, I will not be able to acquire them.” Miles thought out loud.

“Exactly.” Adam nodded and sighed. “I am the head scientist when it comes to serums, and will support you no matter what, but I might not be able to get my hands on required plants to create the serum you require. As I taught you already, plants that need to craft serums are a rank higher for most cases. For the weakest Crown-Rank, low-tier serum, I will need Blest-Rank, low-tier Plant type core, other plants and some other auxiliary herbs.”

“Blest-Rank?” Miles questioned in surprise. “You named it already?”

“It is not certain yet, but it should be this.” Adam scratched his chin and continued, “As of now we can only go as far as C-Circle. Do you know why?”

“Endless Mountain?”

“Exactly.” Adam nodded and a picture appeared in the air. It was a mounting going as far as the eye can see. The top of the mountain couldn’t be seen from the fog, but it was tens of thousands of meters tall. “Endless Mountain surrounds B-Circle , and it is impenetrable. We tried to make a hole in it for years now, but still can’t make even a dent on it.”

“Why not fly over it?” Miles questioned with a ‘duh’ expression. “Tens of thousands meters is tall, but we can create crafts that can leap over it right?”

“Smartass.” Adam flicked his finger on Miles’s head.

“Ouch! Stop Uncle!” Miles cried in pain.

“The gravity on Endless Mountain is unfathomable. A leaf can crush like a meteor as soon as it is over the mountain.” Adam said and showed a video. It wasn't a certified video as there was no way to certify it. But since it was Adam showing it, Miles believed it.

In the video, a silhouette of a human standing on a flying bird could be seen. Man was standing thousands of meters in the air. He wasn’t that far from the endless mountain, but he wasn’t that high so the fog wasn’t blocking the view. Then the human pulled out a paper plane and threw it towards the mountain.

The paper plane glided towards the mountain and it looked weightess. But as soon as the plane arrived just near the mountain, it plummeted to the ground like a fine iron dropped from out of space. It crashed so hard, dust and debris flew into the air.

“The fuck?” Miles blurted out.

“Language.” Adam flicked his finger once again.

“Fine! The heck?”

“I know it is hard to believe, but I saw it with my own two eyes.” Adam sighed with a heavy expression.

“Not being able to pass through the mountain doesn’t mean humans can’t advance into the next level right? Maybe the key is in strength.” Miles theorized.

“Once again, smartass.” Adam rolled his eyes. “You know monsters can’t leave their circles right?”

“Yes.” Miles nodded. It was a common fact.

“It gets worse as you go further into the Portal World. At C-Circle, monsters at Chaos-Rank can never leave C-Circle. As soon as they are forced to D-Circle, they die in unexplainable agony.” Adam answered and the video changed. Miles saw a small cat like monster writhe in pain, as it bled from all over its body.

“It is almost the same for humans. Although we are not as restricted as monsters, at this point, we cannot go back to outer circles. Do you understand what that means?” Adam counter asked.

“If someone were to advance and still fail to pass through the mountain, they would die.” Miles answered.

“Exactly!” Adam nodded in content. “But there are always brave fools.” He sighed.

“Someone tried?” Miles couldn’t help but gasp in surprise. Who would risk their lives for such an unknown.

“Yes!” Adam nodded and explained, “We pinned a criminal, a chanter, in Portal World when we came upon him in luck. When he tried to escape but failed, and pushed to the Endless Mountain, he chose to advance forcefully. As soon as he advanced, he started to bleed from seven orifices. In pain and despair, he tried to climb the mountain but still failed to raise a finger as soon as he was near the mountain.”