Rizevim and Euclid stayed together inside Agareas Island, which was stolen by Diehauser previously, and they moved to the corner of the world. Naturally, there was a reason why they needed this island, and that reason was those creatures before them.

"Hahaha... I can see that everyone will be crying when we let loose everything inside~!" 

"It's as you say, Rizevim-sama." 

Unlike in the original, where Rizevim and Euclid gained the help of the Evil Dragons, which they reincarnated by using the Sephiroth Graal, in this world, they didn't have any help at all, and they had been relying on each other to grow up until now. 

Or rather, it was all Euclid's work, and Rizevim only made an order before being executed by Euclid. 

Yet, unlike Rizevim, who sought chaos and destruction in the world, Euclid wondered whether there was a point for Rizevim to be so focused on all of those things. 

Still, if there was a reason why Rizevim chased after this chaotic life, it was because he was the son of the original Lucifer. He was bored, and because of this, he wanted to make everything less boring. From inflicting harm to the weak, bullying, manipulating his children, using his mother, destroying the world, and then traveling to another world. 

Rizevim, who had everything, only wanted to do whatever he wished. 

Nevertheless, his last wish to go to another world should be able to achieve with the help of Issei. 

Because of this, Rizevim tried his best to help Issei as he also wished to destroy this world and another world. 

Anyway, he just wanted to do whatever he wished to do. 

He was simply an element of chaos. 

Meanwhile, Euclid was more interested in the parallel world and time manipulation. Instead of going to another world and destroying the world, he wanted to go to the past so that way; he could return to his big sister's arms instead of hiding like a rat in the sewer. 

Yes, Euclid had "Sister Control," and he wished to get his hands on his big sister, Grayfia. 

Yet, such a thing was impossible, especially when Euclid heard that Grayfia had become Riser's maid. With Riser's nature, it was definitely impossible for anything to happen, and he was sure that Riser played with the widow of the dead previous Lucifer. 

Thinking about those things made him feel a hatred toward Riser, and Euclid just wanted to kill Riser. 

So, even if Rizevim's plan was troublesome, Euclid did everything to support Rizevim. 

As for Diehauser, who died?

Haha... they thought that guy was stupid for being played by Rizevim's lie. 

Anyway, as they got their hands on Agreas Island, they did everything they could. The first thing they did was to create and create mass-produced Boosted Gear Scale Mails. 

Yes, they created a clone of Issei, who had gained the power of Chichigami within him. 

They weren't sure how Issei could lose part of his DNA, but as they had gotten it, they wouldn't let go of this chance and quickly used his DNA to create clones of this perverted Red Dragon Emperor. 

Yes, Issei might be perverted, and he might have lost to Riser previously, yet when they saw the last battle between Issei and Riser, they knew how powerful Issei was. As long as they could create an army of Issei clones, they knew that the destruction of the world was near. 

Frankly, if they thought carefully, they would feel something was amiss and strange as they could get everything so smooth. Everything, whether it was their evil plan, funds, or research, was so smooth that it was so scary, yet Euclid or Rizevim didn't care about those things, and they were just happy with their success. 

Yes, Riser might be able to defeat Issei, but what if there were a lot of Issei's clones?

When they thought of an army of Issei clones, they felt happy and excited about their future. 

Still, this wasn't the end, as they also got their hands on another thing, and this thing was more dangerous as it was something that had caused the God of the Bible to die. 

666. 

Trihexa. 

Or the Apocalyptic Beast. 

This was what they had gotten and was also the reason why they got their hands on Agreas Island. 

Due to how powerful and dangerous Trihexa was, the God of the bible decided to seal it by using God's everything. 

If it was before, this unseal might be hard to unseal, and they needed the help of Rossweisse to unseal this, but somehow, Euclid felt like he could unseal this beast easily as long as he was given time, especially when the Agreas city. 

While it might be strange why they robbed this most popular city owned by the Agares House, there was a reason why they did this, and that reason was that this city held all the technology of the Old Satans. 

Due to the last Devil Civil War, many of the Old Satans died, and it was also due to this that many technologies in the past had been lost. 

That should be the case, but those technologies still exist within this city. 

It was also why Ajuka had been holed up in this city, as he wished to understand those technologies.

Yet, even if Ajuka had been staying in this city for quite a while, the only things that he had created were the "Rating Game" and the "Evil Piece." Meanwhile, Euclid, who had only stayed in this city for a while, was already on his progress to unleash the beast that was capable of destroying the world. 

Still, as Rizevim and Euclid were excitedly ready to unleash the Trihexa on the world, the two of them suddenly felt a powerful force before dying without being able to say anything. 

Yes, it was Riser who had killed them. He suddenly appeared and killed the two easily before he looked at the creature that was about to be unleashed by the two. 

"This thing is dangerous," Ophis, who came with him, said as she looked at the Trihexa. 

Trihexa's appearance was intimidating. 

It has the shape of a giant beast with characteristics coming from different animals like a lion, a leopard, a bear, a dragon, etc. It has seven necks, seven heads, and ten horns, as well as seven long, thick tails of different shapes. It also has four stout arms and two legs that are even thicker than its arms. Its main body is that of a primate leaning forward. It is covered in black fur and what appears to be scales all over its body. Its size is well over several hundred meters, making it significantly larger than even Great Red.

Moreover, as expected, when Riser appeared, this beast had already woken up. 

"ROOOOOARRRRRRRRR!!!" 

Trihexa grinned as he stared at Riser and Ophis dangerously, wishing to eat them. 

Riser only stared at this beast plainly and said, "Ophis, wait here. Don't let anyone enter." 

Ophis's eyes widened, and her small hand reached the hem of his shirt. "I will go with you." 

"Thank you, but stay here. This is my battle." Patting Ophis head, Riser was different from the original protagonist, who would use the power of this Infinity Dragon without a care. He wasn't going to rely on anyone, and he was going to devour this beast with his own power. 

"Just wait, okay?" 

Hearing his words, while Ophis didn't want to, she could only agree. 

Then, as the seal of the Trihexa was broken, Riser said, "Duelist." 

At that moment, Riser and Trihexa disappeared from this world.