Epic of Caterpillar

The System Master frustratedly had to lower himself to ally Kireina in al of this, after thinking she could be his toy to moving her into an enemy, now going back to becoming her ally was a complete circle! He felt completely and utterly pathetic to even think he had to do such a thing, but he had no other way around it, Kireina was way too incredible and awesome, and he had to lower himself to her gracefulness, especially because she had two overpowered allies- no, three, not only Flora and Aura, but Rimuru was also a formidable ally now!

He had to regretfully admit that Rimuru was now a threat, the cute slime wife that Kireina had, the one that nobody ever saw as a true threat, the one that everyone thought was a mere side character… she ended becoming such a strong Supreme Goddess! And well, eventually and with time, every single of Kireina's family members would also become formidable Supreme Gods anyways… it was a matter of time!

But Rimuru surprised the System Master the most because she was originally brought to life as a summon, a being summoned from a low-grade skill Kireina acquired by becoming a damn Undine Butterfly… She didn't even had a soul before and developed one naturally through training, to think that a formerly soulless being would one day rise to supreme goddess left the system master speechless.

Yeah, she used Kireina's help, but Rimuru was also incredibly talented, this was also a reason she got into supreme goddess before everyone else in Kireina's family, while she got here, the rest was still struggling to surpass the requirements, and it might take them a long time to reach there unless they do something outrageous.

Meanwhile, Rimuru used Kireina's help but also developed her powers greatly to the point that she grew in the monster she was now! Rimuru was the best Slime in the entire world now, and perhaps the best in the Universe as she developed further into her own unique existence.

"To think that this pathetic being from a low-grade summoning skill that didn't even had a soul before would turn out to end as a Supreme Goddess in not so much time! What are the odds for this?! Even with Kireina's help, this is way too out of ordinary! Was this being… incredibly talented from the very beginning?!" wondered the System Master.

Aside from her, there were all sorts of things frustrating him to the point he began to rage once more. The System Master had a terrible temper and an even more terrible way to deal with it…

"I can't believe I've been reduced to such a pathetic side character! I really thought I would become more important in this Universe, but Kireina is easily overshadowing me with her stupid siblings! I am also technically her family, does that means I should at least get some more spotlight?!" asked the System Master.

"I think you've overexaggerating a bit, stop reading so much human fiction for one." Said Lucifer.

"Aghh! I just want to get out of this damn world already! With your help we can get out temporarily but like a vacuum, this world just pushes us back…" sighed the system master.

"Well… Oh?"

Suddenly, Lucifer felt something.

Within the realm he reigned, the Plane of the Gates of Hell, there was a different entity there, doing something…

No, various entities.

"Invaders." He said.

"Hm? What?" asked the System Master.

Lucifer looked down with a bit of contempt but then relaxed.

"It seems that the invaders, these skeletons from the Netherworld Plane went into my Plane too, they're very active, huh? For being a bunch of undead they're really something…" he sighed.

"Wait, the Necrotic Death Lords, the allies of Hel?! They're going to your own Plane? Do they want to get burned alive?" asked the System Master.

"No, they have made a contract with an Undead Archdemon Avatar and they're using it as the anchor into my Plane, very clever. These stupid Archdemons always leaving their trash behind for others to do whatever they want… Kireina ate one of them and became an Archdemon herself, not like I minded that, but now that these idiots grabbed it, it really makes me feel a bit frustrated." Said Lucifer.

"What do you plan to do then?" asked the System Master.

"Hm? Me? Nothing for now, not worth the hassle to be honest, I would rather dedicate myself to work hard in my own things to be honest… for now I will do what I always do and that's about it. my true self could easily wipe them out but there's no point in wasting my energy in such a thing. I am not fond of my own Plane anyways. Its just a prison." Said Lucifer.

Indeed, Lucifer's Gates of Hell were a prison, his story goes far eons ago, as many that have heard about his story in the biblical records, Lucifer was the most beautiful, prideful, and intelligent of all Archangels made by God (The One), however his arrogance made him turn himself against his own father as he believed himself to be more fitting of being a God than him.

He thought of his father's rulers to be way too passive and that humanity needed to be punished even more for what they did, they needed to inflict punishment and also interfere in their affairs… but this ended badly for him, even with all the Archangels that agreed with him, he was defeated by The One's power, and the Primordial Deity created a Interdimensional Prison to confine his unruly son inside, sealing his body there in the Gates of Hell, where all sinful souls would go to take their punishment in the afterlife.

Demons naturally were born from the hatred and emotions of Lucifer, like a pest that surrounded him, evolved, and turned out to be their own race of beings… the Archdemons also came to be there, some were Archangels, but others were simply Demons that grew to such strength…

Therefore, Lucifer has never been fond of "his home" and only see it as a prison, he didn't care whatever other beings did with it.