Beyond the Diabolical Dragon Palace were dozens of gigantic palaces.

Each palace was as wide as a lesser realm. Among which, those palaces belonging to the three 7-heavens demon king were the largest and closest to the Diabolical Dragon Palace.

The palaces within the Underworld Dragon's Den were arranged like stars surrounding the moon with the moon being the Diabolical Dragon Palace.

Next to the Diabolical Dragon Palace, one could see three gigantic palaces for the three 7-heavens demon kings followed by nine palaces for the 6-heavens demon kings. Furthest out were over thirty palaces for 5-heavens demon kings. Together with the rest of the palaces, they formed the vast and majestic Underworld Dragon's Den.

One could say that the entire Underworld Dragon's Den was over a hundred times larger than the Jambu Realm where Wu Yu was born.

"There are great void immortal designs around the palaces for 6-heavens demon kings and 7-heavens demon kings. They aren't concentrated and we could still observe from a distance. However, entering wouldn't be possible."

"For the palaces of 5-heavens demon kings, we are able to enter without drawing the attention of the demon kings within the Underworld Dragon's Den."

Realizing the circumstances, the trio could only hide for a period within the Underworld Dragon's Den first.

To observe and see if they could get any relevant information.

Basically, they had to first find out the level of strength of the countless demon kings within the Underworld Dragon's Den. Full Moon of Nanshan scouted in the shadows using his Gone from the Skies. From time to time, he would see demon kings exiting their palaces.

Soon, Wu Yu and others were able to grasp the information of some compelling demon kings within the Underworld Dragon's Den.

For example, Baize Demon King was one of the few 6-heavens demon kings and his true form was the fusion of a mountain goat and unicorn. He tread on clouds when moving and his true form was always masked by layers of ominous clouds. If it wasn't for the ominous clouds, one might mistaken him as an immortal beast because of his snow-white fur.

TN: Baize is a mythical beast from chinese mythology.

Baize Demon King was one of the nine 6-heavens demon kings in the Underworld Dragon's Den and a close aide to the Diabolical Dragon King. From the memories of the Primitive Demon King, Wu Yu knew he often travelled to handle matters for the Diabolical Dragon King. For matters relating to cultivation resources, Baize Demon King had always been personally involved.

Although they were both 6-heavens demon kings, Baize Demon King was a subordinate of the Diabolical Dragon King. Even when they were outside of the Fiendish Underworld Metropolis, his status and standing were a lot higher than other 6-heavens demon kings in the wild.

For example, the group competing for the eternal demon emperor's corpse in the black sea previously, including Black Yama Demon King, Primordial Forbidden Demon King, Dreary Gold Demon King and Golden Rhino Demon King, would treat Baize Demon King with great respect whenever they met him.

The force behind Baize Demon King wasn't to be messed with. Although Baize Demon King would often ignore these demon kings, they were still cautious not to offend him. Otherwise, they might just find themselves dead and exposed in the wild.

This was also why Diabolical Dragon King could form such a powerful demon immortal faction, their coalition in deed only bred greater fear and might as they banded together.

Within the Fiendish Underworld Metropolis, the weakest was at least at the Immortal Lord Realm. Only those at the level of demon lords had the rights to serve the Diabolical Dragon King and lived within the Fiendish Underworld Metropolis.

Other than Baize Demon King, Wu Yu and others had also seen other 6-heavens demon kings of the Underworld Dragon's Den.

For example, there's a demon king whose true form was 10,000 Immortals Kunwu and known as Kunwu Demon King. Of those within the Kunwu demon beast origins, his bloodline was among the best. Wu Yu had seen similar demon beasts of Kunwu origins such as the Three Immortals Kunwu when he was in the Jambu Realm. However, in terms of the nobility of bloodline, those couldn't be compared to the 10,000 Immortals Kunwu of the Underworld Dragon's Den.

The abilities of the 10,000 Immortals Kunwu was slightly stronger than Baize Demon King. Among the nine 6-heavens demon kings of the Underworld Dragon's Den, his battle capacity was also among the top.

When 10,000 Immortals Kunwu left its palace and head out to run errands, Full Moon of Nanshan wouldn't dare to even breathe loudly. After all, they would be dead once they were discovered.

The 10,000 Immortals Kunwu was shrouded in pitch-black clouds and rode black bolts of lightning. His eyes were intimidating and ordinary demon kings would probably shuddered in fear when facing him. It was said that the 10,000 Immortals Kunwu could even go against 7-heavens demon king and stand a fair chance of winning.

Fortunately, Full Moon of Nanshan's Gone from the Skies was indeed incredible and wondrous. Even though the 10,000 Immortals Kunwu was passing by just next to him, he didn't find anything amiss or notice Full Moon of Nanshan was just hiding next to him.

There's also a Three-Eyed Qiongqi known as Qiongqi Demon King. This 6-heavens demon king had three eyes and was always circled by streams of black mist that obscured his appearance. To this point, Wu Yu and others realized those demon kings found within the Underworld Dragon's Den, including those 5-heavens demon kings, had mainly inherited the darker bloodline of immortal beast tribes.

TN: Qiongqi is one of four famous fiendish beasts in chinese mythology.

Taking Baize as an example, there were also immortal beast Baize in the sky palaces. However, the one in the Underworld Dragon's Den had energy that was darker. Therefore, it couldn't ascend to the sky palaces and instead had to ascended to the Demon Immortal Realm.

No one knew the current situation of the Demon Immortal Realm was so unpleasant. Therefore, these demon immortals, who had a more defiled bloodline of immortal beasts, were probably overwhelmed by grievances after ascending to the Demon Immortal Realm. At the same time, their desire to become eternal demon emperors were more intense than others.

When Qiongqi Demon King headed out for a mission, Full Moon of Nanshan didn't dare to peek through the black mist to see the appearance of his true form. All Full Moon of Nanshan could see was the fiendish glow that glittered in the three eyes.

There's also a Crimson Moon Kunpeng.

TN: Kunpeng is a gigantic mystical beast that is both a roc and fish in chinese mythology.

There were even more immortal beasts that were of Kunpeng origins. However this Crimson Moon Kunpeng was a unique breed within the Kunpeng lineage. His entire body was the color of bright-red blood and it seemed that there's always blood oozing out of him. Between his brows was a fiendish-looking crimson crescent image.

Most likely, the crimson crescent had something to do with the Mystique of the Kunpeng Demon King.

Naturally, Wu Yu and others definitely couldn't witness the abilities of these demon kings within the Underworld Dragon's Den. This was because the Diabolical Dragon King had strictly forbidded demon kings from infighting within the Underworld Dragon's Den.

Therefore, Wu Yu didn't have a good sense of the battle strength of those 6-heavens demon kings. Nonetheless, judging from their auras, these 6-heavens demon kings should be several levels stronger than those wild demon kings contesting for the eternal demon emperor's corpse in the black sea.

In fact, Black Yama Demon King together with Primordial Forbidden Demon King might not even defeat a 6-heavens demon king from the Underworld Dragon's Den.

These were also the benefits of serving Diabolical Dragon King. In terms of cultivation resources, they had it a lot better than those wild demon kings. Moreover, the average age of these 6-heavens demon kings were a lot lower than those 6-heavens demon kings in the wild.

The main factor was the need to pay tribute to Diabolical Dragon King every hundred years. Moreover, one would have to take orders from Diabolical Dragon King and his freedom would be restricted in everyday's life. Therefore, some 6-heavens demon kings in the wild wouldn't want to join Diabolical Dragon King. Primitive Demon King was an example.

After observing for several months, the trio also realized the demon kings in the Underworld Dragon's Den also kept female demons in their own palaces. These female demons would specially serve the demon kings and would likely not ever have the opportunity to step out of the palaces in their lifetimes.

From time to time, some demon kings would get together to party and have fun. More often than not, the demon kings would be cultivating in their palaces or be fooling around with the female demons in their own palaces.

Whenever the demon kings gathered, Full Moon of Nanshan would get closer intentionally to find out if they were discussing about Jiu Ying.

However, he didn't hear any information relating to Jiu Ying even after several months. Basically, those 5-heavens demon kings in the Underworld Dragon's Den weren't either not interested about Jiu Ying or had not been in contact with information relating to Jiu Ying.

As for the 6-heavens demon kings, they were almost always on their own and rarely met up to discuss anything.

Even if they headed out to run errands, they would return swiftly and enter back into their palaces. It was hard for Full Moon of Nanshan to get any information from the 6-heavens demon kings.

Therefore, 5-heavens demon kings were the main source of information for Wu Yu and others. The only shame was that they didn't learn anything about Jiu Ying from them.

"If this goes on, it probably wouldn't do. We have to find a way to devour a 5-heavens demon king and get his memories."

Wu Yu was annoyed. After all, nothing was known about Jiu Ying for now. Jiu Ying might be in grave danger at this moment and yet he was completely blind to it. He had to find a way as soon as he could.

"If we try something within the Underworld Dragon's Den, we would definitely alarm the other demon kings. Although the palaces of in the Underworld Dragon's Den are huge, it wouldn't be a problem for the demon kings. We have to find the right opportunity." Full Moon of Nanshan gave his analysis.

Regardless, they definitely couldn't do it in the Underworld Dragon's Den. Now, they just had to wait for a 5-heavens demon king to head out for errands.

At the same time, they would be trying to find out more about the Underworld Dragon's Den to see if they could get anything.

Finally, all the 5-heavens demon kings gathered together on one day. This unexpected development was a surprise for Wu Yu. There would likely be something grave for all the 5-heavens demon kings to gather together.

Full Moon of Nanshan concealed himself at one corner while eavesdropping. Soon, he found out the once in a century day, when the Diabolical Dragon King would be collecting tributes, was on the horizon.

The thirty-five 5-heavens demon kings ruled over several thousands of demons. Each 5-heavens demon king had a namelist to collect the tributes from once in a hundred years. Only by paying sufficient tributes would one be qualified to remain in the Fiendish Underworld Metropolis.

Wu Yu knew about this previously. What he didn't know was that this was happening soon.

"In that case, I might have the chance to devour a 5-heavens demon king that is heading out to collect tributes. I would then be able to have his memories!"

Wu Yu started plotting in his mind. However, the exact circumstances would still have to be dependent on the schedule of the 5-heavens demon kings heading out to collect tributes. There were also areas that he needed to pay attention to. Therefore, the trio didn't get ahead of themselves. Instead, they continued hiding in the dark while listening in to the conversation of the 5-heavens demon kings.