Attendance… plz…)
….
Different worlds, same rules: Phantasmal Species parts were top-tier crafting materials. That was an immutable fact.
Rimuru, possessing the [Split] racial skill, could easily separate a portion of his body while keeping the cells alive and active. The problem, however, arose during the integration process.
Upgrading a Mystic Code wasn't just slapping a +1 sticker on it. Changing its fundamental nature was excruciatingly difficult. It basically meant scrapping the original design and rebuilding it from the ground up.
Today marked the 284th failure.
An entire week had passed without him noticing.
"Phew. Magical research really is a time sink. It's dangerously addictive."
The transparent water bird on his shoulder fluttered its wings and took flight, dissolving into the air. Rimuru stepped out onto the balcony, narrowing his eyes as he basked in the sunlight.
He watched the bird reform in the distance, falling into deep thought.
His old self had been limited by his sealed memories. He had been content with just making Boundless a tool that could mimic various shapes based on vague dreams.
But Rimuru? He was pragmatic. And he was greedy.
He knew the plot. He knew about the absurd Noble Phantasms that existed in this universe, and the countless artifacts from other fictions in his memory. He knew exactly what kind of Mystic Code he needed.
It needed potential. It needed raw power. And most importantly, it needed to be an exclusive, growth-type weapon that only he could wield.
"Water has no form, so it can become anything... but water also accepts all things. It can swallow everything."
Rimuru chuckled softly. "My previous vision was too narrow."
If Rimuru himself could devour corpses to plunder their skills via [Predator], then logically, his weapon should be able to devour other weapons to plunder their abilities and forms.
To achieve this, he had even tried to learn Projection (Tracing) magic and Plunder magic. The results were lackluster. He quickly realized that Emiya Shirou's Projection was only broken because of his Origin: "Sword."
So, Rimuru had asked the Great Sage about his own Origin.
As expected, while the Great Sage couldn't fully pierce the veil of the Root, she could calculate the parameters. Given the overwhelming influence of his [Predator] and [Great Sage] unique skills on his soul, the answer was obvious.
His Origin wasn't Water. It wasn't Sword.
It was Predation. Or perhaps Gluttony.
This confirmed his ambition.
Research never yields results overnight, but persistence breaks down walls.
Over the last week, Rimuru had conquered problem after problem. He had strengthened the structure of Boundless, solved the issue of material fusion, and even managed the conversion of abilities.
He was one step away from success.
And that was where he hit the hardest wall.
Bio-Compatibility.
He couldn't maintain the long-term biological activity of the slime cells once they were fused into the water base.
When he used [Split], the separated slime was like a clone, it was alive and connected to his consciousness.
But once he tried to forge it into the Mystic Code, the process essentially killed the cells. It was no different from butchering a cow to make leather armor.
This was fatal to his plan.
The core of Rimuru's [Predator] skill was to swallow, digest, analyze, and then simulate.
For Boundless to inherit this trait, the slime cells inside it had to remain alive to perform the digestion.
Then, using the Great Sage as a processing hub, the mana could be restructured to mimic the devoured weapon.
It was a bit of a hack, relying heavily on his specific cheat skills, but it was the only way to build a growth-type weapon in such a short time.
Plus, it ensured exclusivity, without the Great Sage to process the data, the weapon would be a useless brick to anyone else.
"The magical capacity and Mystery level of the 'Boundless Water' is just too low," Rimuru muttered, staring at the reforming water bird.
"It can't sustain the separated slime entity. It suffocates the cells."
He wasn't just talking to himself; he was communing with the Great Sage.
"But if I swap the base material to something else, I lose the 'Formless' property of water, which defeats the purpose of shapeshifting."
"What a pain... Is this really the highest grade of Boundless Water available in the market?"
"It's too weak."
[...]
The Great Sage fell silent for a moment.
As a self-learning AI, the Sage had evolved significantly over the past week.
She had graduated from rigid, systemic notifications to mimicking human logic, and even throwing the occasional shade, just like the Great Sage Rimuru remembered from the anime.
[Perhaps we can invert the methodology.]
"Hm?"
The blue slime-boy, squinting comfortably in the sunlight, paused. He opened one eye. "Invert how?"
[We are currently limited by the capacity of the Boundless Water. We are trying to force a high-grade material (your cells) into a low-grade container (the water). Why not reverse it?]
[Why not use your body as the primary material and integrate the Boundless Water into it?]
"..."
Rimuru's first reaction was That's impossible. But a split second later, realization hit him.
Wait. That's actually genius.
[However, this would necessitate a complete reconstruction from scratch...]
"No need to be so dramatic."
Rimuru focused his will, summoning the water bird back to him. It landed on his palm, reverting into a wobbling sphere of liquid.
Gulp!
He tossed the entire Mystic Code into his mouth and swallowed it whole.
A cool, sweet sensation burst in his mouth before sliding down his throat.
"Analyze it, Great Sage."
Aside from the [Stomach] being an infinite storage inventory, Rimuru remembered another broken ability from the original series.
True 3D Printing.
As long as he had the raw materials and the analysis data, he could mass-produce copies of anything he had devoured within his stomach.
….
Meanwhile, in the hallway outside Rimuru's room.
May Riddell was holding the hand of a tiny girl, perhaps five or six years old. She crouched down, her expression stern as she gave a final briefing.
"Elair, listen to me. When you meet Professor Rimuru in a moment, you must be obedient. You must greet him politely. Do you understand?"
"Mhm! Mhm!"
The little girl, Elair, blinked her huge eyes and nodded vigorously. She had platinum-blonde hair and a prominent ahoge(cowlick) that bobbed with her movements. She looked like the picture of innocence.
But May knew better.
Beneath that angelic exterior hid a lawless demon king. If May had to describe her, "Arsonist" and "Terrorist" would be understatements. If May's teacher hadn't been keeping a close eye on the brat, the entire Archelot estate would have been blown to the moon by now.
May could still vividly remember the look on the servant's face when she picked Elair up today. The servant had wept tears of gratitude, looking like a prisoner of war finally being released.
Ugh. I honestly don't know if giving this kid to Rimuru is a favor or a curse...
May hesitated. But objectively speaking, Elair's affinity for Water Magecraft was terrifyingly high. Combined with her Witch bloodline, barring any accidents, she was guaranteed to reach the rank of Brand (Color) in the future.
Steeling herself, May stood up and raised her hand to knock.
But before her knuckles could graze the wood, a shout of pure joy erupted from inside.
"Haha! It worked!!"
Rimuru was happy.
By analyzing the structure of Boundless directly inside his stomach and then synthesizing it with a split portion of his own slime body, he had solved everything.
Not only was the "biological activity" issue resolved perfectly, but the Mystic Code now maintained a permanent, living connection to his main body.
In short: Boundless was now literally a part of him. It could hide inside his body when not in use.
However, due to the material swap (Slime cells > Water), the appearance had changed. The original clear, transparent water orb was now a translucent, light-blue jelly. Instead of feeling like cool, flowing water, it was now bouncy and elastic.
Squish, squish.
It looked exactly like a mini-Rimuru. But functionally, it retained the "Formless" ability to shapeshift into anything.
And the best part? Because it was connected to his main body, the data link was seamless.
Whether Rimuru devoured a weapon with his main body, or Boundless devoured a weapon independently, the data would be shared via the Great Sage's simulation.
This meant Boundless could instantly transform into any weapon or Mystic Code he had analyzed.
"So this is it… huh," Rimuru grinned, holding the blue blob. "An infinite arsenal."
….
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