In the end, Riezel, under extremely unwelcome circumstances, successfully entered the Great Tomb of Nazarick again.
Unfortunately, Riezel did not get what he wanted because Ainz didn't want to open the 8th Floor. It seemed that Ainz could no longer bear the cost of reopening the 8th Floor, so he strongly opposed Riezel's barbaric request and eventually made Riezel agree to step back.
"Okay, not opening the 8th Floor is fine, but you have to let Rubedo out to fight me, and you also have to lend me your Floor Guardians and high-level servants."
Needless to say, this was Riezel's compromise, and if Ainz still refused, he would force it.
Perhaps Ainz could sense this from Riezel's attitude, so although reluctant, he had no choice but to agree to Riezel's request.
"...I'll lend them to you, but you can't kill them."
It was inevitable because resurrecting NPCs required considerable resources.
"Okay."
Riezel readily agreed to Ainz's condition.
Ultimately, Riezel temporarily settled in the grand arena known as the Amphitheater on the 6th Floor of the Great Tomb of Nazarick, battling NPCs like Rubedo, Shalltear, Albedo, and Cocytus every day.
However, the battles were mostly team battles, or more precisely, one versus many, where Riezel was always alone, while at least three from the Great Tomb of Nazarick participated each time and never dueled him one-on-one.
In addition to the Floor Guardians, the Great Tomb of Nazarick sometimes sent out high-level heteromorphs, mostly above Level 80, forcing Riezel to fight fiercely on the 6th Floor.
Even though the noise the battle caused wasn't as unprecedented as the last battle on the 8th Floor, it was no less spectacular and made quite a stir.
Under these circumstances, many from the Great Tomb of Nazarick, led by Ainz, were shocked to find that Riezel's strength had indeed grown.
However, it was not the so-called 'a little stronger' that Riezel had claimed, but more like a transformation, where he became much stronger than before, even able to overpower Rubedo, the strongest NPC in the Great Tomb of Nazarick.
'From now on, I swear I'll never get into conflict with this damn monster again.'
Ainz silently observed for a while and, while sweating coldly, made this decision.
Ten days passed quickly as Riezel fought fiercely on the 6th Floor of the Great Tomb of Nazarick.
Perhaps because his opponents were strong, Riezel successfully adapted to his new strength in just ten days, eliminating the previously overwhelming sense of disharmony.
Not only that, but Riezel also took the opportunity to learn some magic spells he hadn't seen before from the NPCs and high-level heteromorphs of the Great Tomb of Nazarick, taking advantage of Nazarick once again.
Needless to say, this dimensional travel left Riezel with plenty of gains.
Not only had he achieved his original goal of leveling up and improving his strength, but he had also acquired a variety of magic.
Before this dimensional travel, Riezel's swordsmanship had already surpassed his magical abilities, but after this dimensional travel, his magical abilities had not only caught up with his swordsmanship but might have even surpassed it.
'Looks like this dimensional travel is also a big success.'
Riezel thought with deep satisfaction, finally leaving the Great Tomb of Nazarick and returning to the surface under the expectant gazes of Ainz and the others.
Ainz had been using surveillance magic to monitor Riezel until he was sure Riezel had completely left the vast grassland, and only then did he slump down on his throne and give orders to Albedo and Demiurge.
"From now on, all external operations initiated by Nazarick will be temporarily suspended. Aside from my side, which can still operate through Darkness as Momon, only Demiurge is permitted to fully handle the covert operations regarding the Re-Estize Kingdom, the Slane Theocracy, and the Baharuth Empire."
"Everyone else is to return to Nazarick immediately, and afterward, Nazarick will be sealed off from the outside."
"Please... for the sake of everything, don't let us encounter that monster again!"
"Did you hear me?"
Ainz's orders were met with responses from all the NPCs that practically screamed their relief.
""YES!""
Clearly, Riezel had become a psychological trauma for all the inhabitants of the Great Tomb of Nazarick.
Even if time passed, this trauma might never fade.
===
[Warning, the time limit has reached zero—dimensional travel is about to conclude.]
[Initiating inspection.]
[User is detected possessing unique powers from this world—they will return with the user after dissolving the consciousness body.]
[User is detected carrying unique items from this world—if you wish to bring them, it can be accomplished by consuming dimensional energy.]
[A list of unique items has been compiled—please proceed with your selection.]
[1: Caloric Stone (20)]
[2: Origin Ring (6)]
[3: Wyvern Amulet (2)]
[4: Giant's Glove (2)]
[5: ...]
As Riezel left the vast grassland where the Great Tomb of Nazarick was located and strolled through the forest, he received the long-awaited message.
'Origin Ring? Is that the name the Dimensional Magic Cube gave to the magic ring?'
It was understandable, since in the original work, the magic ring Riezel got from Gazef didn't have a proper name, after all.
Riezel smiled faintly and then glanced at the remaining dimensional energy without attachment or regret.
[Dimensional Energy: 353]
Before initiating dimensional travel to this world, Riezel's remaining dimensional energy had been 203 units, and the time ratio for this dimensional travel was 1:150.
In other words, Riezel had stayed in this world for 150 days—five months in total.
As a result, his dimensional energy had accumulated to 353 units.
'It has already surpassed 300?'
Riezel's heart was lightly stirred.
Why?
It was simply because the Dimensional Magic Cube could open dimensional travel to a designated world.
In other words, Riezel could use this function to return to any world he had visited before.
However, opening dimensional travel to a designated world required consuming ten times the dimensional energy.
Previously, 30 units of dimensional energy could open a normal dimensional travel, but for dimensional travel to a designated world, it would require 300 units.
Now, Riezel's dimensional energy was enough to open dimensional travel to a designated world, which made him start to miss the world of Danmachi and his companions from Loki Familia.
So far, Riezel had traveled through three worlds—the world of Danmachi, the world of Demon Slayer, and the current world he was in, the world of Overlord.
However, the latter two worlds hadn't left Riezel with much attachment.
In these two worlds, Riezel had only done everything he needed to do and gained the growth and achievements he sought, so he probably wouldn't return to them again. Only the world of Danmachi, only Loki Familia, where there were many things he couldn't let go of.
'Is it time to head back?'
Riezel was lost in thought, facing a dilemma.
'Forget it, no rush.'
Riezel ultimately suppressed the homesick-like emotions that surged within him.
'Knowing there's a time difference there, it's probably only been a few days, right?'
If the time spent during Riezel's dimensional travels was factored in, he had probably been away from the world of Danmachi for about a year.
However, when a year or so was converted with the 1:100 time ratio, it only amounted to three or four days having passed in the world of Danmachi.
Riezel wasn't someone who got overly sentimental, so it wasn't like he was missing anyone to the point of being desperate after just a year. Besides, if he went back now, he would drain almost all the dimensional energy he had managed to accumulate.
'I'll go back after one or two more dimensional travels.'
Riezel came to a decision.
'I'll wait until the dimensional energy doesn't run out after one trip to a designated world, then I'll head back.'
Shortly after making this decision, Riezel began picking out the items he wanted to take with him.
Unlike the last time, there were quite a few things he wanted to take this time.
[Caloric Stone (20)]
[Origin Ring (6)]
[Wyvern Amulet (2)]
[Giant's Glove (2)]
All of these were very useful magic items for Riezel, so he had to bring them all, especially the Caloric Stone and the Origin Ring.
One was a World Item, and the other was an exceptional magic item made by the ancient magic of the dragon race—both incredibly precious, so he couldn't afford to leave them behind.
Even though they required a lot of dimensional energy to take, with the Caloric Stone requiring a whopping 20 units of dimensional energy, Riezel didn't hesitate to take them because of their value and functionality.
With that, Riezel consumed 30 units of dimensional energy in one go.
[Dimensional Energy: 323]
After confirming the remaining dimensional energy, Riezel finished his selection.
[Item selection completed—starting execution.]
[Items assimilated successfully.]
[Dimensional travel concluded—initiating the return procedure.]
As the messages from the Dimensional Magic Cube flowed into Riezel's mind again, his body in this world was eventually dismantled.
Before long, Riezel's consciousness returned to its original state and, through the dimensional channel in his mind, began heading back to the main world.
Riezel Brynhart, the powerful figure who had suddenly appeared and left few traces in this world, finally departed.
However, the impact Riezel left behind in this world did not vanish.
At the very least, the Great Tomb of Nazarick had remained dormant for several decades because of him, and it wasn't until many years later that it stepped onto the world stage.
Surprisingly, the Great Tomb of Nazarick still honored the agreement made with Riezel, not attacking innocent humans but only dealing with high-ranking officials and enemies it faced.
Meanwhile, the famous Adamantite Adventurer Group, Blue Roses, often mentioned a human warrior, claiming he was the strongest being in this world, leaving behind numerous rumors and stories.
Among the human race, a powerful figure was also born, known for his lightning slash, a certain-kill strike, with strength that not only surpassed those in the Realm of Heroes but even outdid the outliers.
He could even stand his ground against the legendary vampire known as Landfall in direct confrontation without falling behind.
He had also defeated Gazef Stronoff, earning the title of strongest warrior, but he always claimed he wasn't the strongest, insisting instead that the true strongest was the young man he had been chasing for decades, who was none other than his mentor.
Riezel Brynhart's name became widely known because of these people, and even after hundreds of years, there were still those who mentioned him.