HDXD: Omni Harem System

"The same goes for that weird inner body armor of yours, my phsycial attacks aren't hurting you at all."

At these world Alustus began to chuckle.

"Hahaha… as expected, you're strong. Physically gifted to an extent, sure. But your hits? They don't even come close to the raw, terrifying brutality of a a King Jroflin. That king class monster was extremely fast for his size, and just as strong."

He admitted, commending Adam on his raw strength.

Then he continued to speak.

"We fought for nearly two weeks straight before a winner was finally decided, and of course that winner was me. And back then, I was still just low B-Rank monster, while he was a peak A-Rank Monster."

He exhaled through his nose, recalling the memory, and immense feeling of victory right after.

"At full power, using his race natrual ability of Enhanced Condition, he could punch with a force that made tectonic plates movements seem like cheap party tricks."

"That fucker nearly sent me past the world barrier when he punch me high in the sky. And back then I used to fear the sky... but now? I've grown to enjoy the perks it brings me."

He gave a cocky grin.

"Point is, in a test of physical strength? He could hit hard enough to shift a continent. And even then, all he managed to do was break a few of my ribs when he launched me skyward."

Alustus cracked his knuckles with a confident smirk.

"...So your punches? They ain't doing shit to me."

But Adam just chuckled right back at him, low and amused.

"Hmm… if blunt attacks won't cut it, then maybe it is time I switched things up."

He raised his gaze, golden eyes glowing with growing madness.

"You've got good offense and defense, I'll give you that. But when it comes to pure versatility? You don't even deserve to stand on the same battlefield as me in that category."

Adam's voice dropped, more serious now.

"So hear me King of the Sidhe, don't you dare think for a second that you've already won this battle just because I can't hurt you with my punches. Because I, sure as bloody hell, have way more ways to kill you than you do me. If punches won't work… then I'll just use every ability I have. One of them is bound to finish you off."

Adam inside his sphere of energy began to spread his arms wide.

"Let's assume a more proper combat form, shall we? Try not to shit yourself once you see it."

In that instant, Adam's monstrous energy exploded outward like a raging storm. The sheer pressure of it should've been impossible for him to control.

But that was the old Adam.

This version of him with his current evolution prove enough for him to counter this weakness to an extent.

He tapped into the Sidhe's own natural abilities, manipulating both internal and external energy through their unique Regulator Rings.

Using their biology as his own, Adam began circulating his boundless reserves of power through his body with terrifying efficiency.

Then came the start of his transformation.

His body, small and Sidhe-sized, didn't grow taller.

There was no need for that, to match Alustus he would need to remain the same height. Agility was the key, and the smaller frame let him hit harder, faster, and easier.

Bones cracked and reshaped.

Muscles tore and reformed.

His veins pulsed with refined, regulated Monster Energy as he used his unique ability, to destroy and rebuild his body anew to construct a battle form specifically tailored to this fight.

Every time his body broke, it came back stronger.

Faster

And Better.

The shockwaves alone from his transformation blasted Alustus backward, forcing a barrier to form just to keep the heat from cooking him alive.

The very air warped.

The ground melted.

Miasma fizzled.

The residual waters around the petrified tsunami began to evaporate.

Alustus narrowed his eyes, his face tightening with unease.

"What the hell is up with his energy reserve? Even I don't have that much. And it's still growing?!"

He growled and called out mentally.

'System, analyze and report. What is his energy limit?'

The System replied.

[Notice: Target's energy reserve cannot be quantified. It appears as a continuous chain of nines across all power metrics. Conclusion: energy source is immeasurable. Most likely classifications, an Outlier/Emperor-class entity with indefinite energy… or, worst-case scenario… a Shinso-class existence with infinite energy]

"...Fuck!!"

Alustus cursed, eyes widening.

But he refused to back down.

"System, is Poseidon fully charged yet?"

[Negative. Current Astrum Level: 99%. Estimated charge time: 3 hours, 8 seconds]

"Tch… So I need to stall for that long? Great."

He clenched his jaw and steeled himself, defiance rising in his glare.

"Well, I've never been one to run from a fight."

Alustus raised his arms, energy flaring wildly around him.

"Come on then you freak. I'll show you the full might of the strongest Sidhe to ever live!"

Meanwhile, Adam was deep inside a cocoon of writhing monster energy, reconstructing himself.

The process was tedious, around thirty seconds of body-melting agony, but with the intense heat radiating from his transformation, he knew Alustus couldn't get close without risking serious damage.

That gave him a window, and he took it.

Inside the cocoon, Adam spoke to his System.

"System, what is the Archive saying about Alustus?"

He asked yet again, earlier he had digged up information on him with the help of the System.

And quickly found out that Alustus transmigrated here, and that his true name is Kagami Renjiro.

But now that he had time, he tried to pry some more.

『Well Master... aside from the fact that he is a transmigrator from this universe's human multiverse, and not an Outsider like yourself, he is honestly nothing special. A Japanese hikomori who died of a heart attack while jerking off to milf hentai with oversized tits』

The system blankly explain causing Adam to chuckle to himself.

He already knows this as well.

"Fucking loser, well I used to goon too, but being jobless and a gooner, with that hikomori factor is just another way to say that your a failure of society who needs divine intervention be worth anything at all."

"Either way, anything else?"

He asked the System, and it replied saying.

『Since you got a direct look at him, I was able to dig through his Archive even deeper. Turns out, he is a System user too. His is called the Offering System』

"The offering system, does it allows him to make offerings or something? If I had to guess a power like that would make the user benefit from these offering of some kind right?"

Adam asked, genuinely interested in how his System differs from his.

And it was as Adam expected, as the System all but confirms it.

And in actuality it was all but obvious.

『Yes my master you are indeed right. The mechanics are simple. He sacrifices things, but to do that, he needs to build altars. So yes, Minerva was technically correct when she called him an Apostle, but he is a very particular kind』

Hearing this, it caught Adams attention, as he questioned further.

"Hmm, how so?"

And the Answer the System gave him was rather surprising.

『He was summoned to this world by a Reality Eater. A special one, in fact...Eros is it name, the son of the Monster King of Force and an Elder Reality Eater. A specific altar he carries doesn't just connect him to Eros… it links him to the entire Reality Eater hive within the Netherspace』

"Ohhh, heheh... So he has a really convient Golden thumb, truly fascinating... Sigh this world is so big, I really want to explore it all one day, in this life I want to see everything, well as much as I can, all the beautiful and chaotic things Beatrice has made in this world."

『And I believe you can』

"Heheh... really you think so?"

Adam smiled inwardly, despite the heat of battle, he was enjoying the small talk he had with the System.

『Of course my master, in this world, if there is anyone more deserving to be happy then it would be you. I don't say this to come off as fanatic because I am connected to you, but it because of you this world you now find yourself in even exist. It goes without saying you deserve to see it both lights of good and bad』

"Heheh."

Adam chuckled happily at the System's words, as he open his eyes, his body starting to finally to take shape into the most optimal form for the fight to come.

"Me oh my, your such a sweet talker System say, after this battle, would you like me to name you. Not going to lie, for the past five approaching on six years since we came here, I have being calling you nothing but System."

This took the System by suprise, as she replied back with an equal positive response.

『Ah? Hmm... I would be honored master』

"Good well then let's end this bastard."

『Yeah let's do it』

"First off answer my previous question."

With that the System got to work.

『Sure, well like I said... Main Character types like Alustus usually have convient Golden fingers. In his case however the Offering System splits his initial abilities into two categories, unlike our harem building power set of entering routes and getting rewarded for entering them』

『Category One: Sacrificial Offering. He sacrifices something, a life, items, skills, energy, at his altar and gets something back in return, depending on who or what he is offering it to. These returns can be skills, blessings, items, even mutations』

"And the second one?"

『Category Two: Self-Investment. A woman-only skill path. After dominating and breaking a woman in, they become addicted to their captor. Once they mentally and spiritually "submit," he can choose to make them his wife, and if he does, this bond satisfies the condition to boost his bloodline potency. That is what causes those accelerated mutations』

『If he keeps doing this… theoretically, he could become the next Monster King of Force. Especially since the Sidhe race are one of the few remaining pure-blood monster races eligible for that title, due to how close their blood ties is to the king』