A Walker from the Nasuverse, Demon Lord Rimuru!

"In this age, when the Phantasmal Species have finished migrating and mystery has grown increasingly scarce, even the lowest-grade Phantasmal Species materials must be extraordinarily top-notch, right?"

The Great Sage spoke in a tone of such admiration that Rimuru felt like she was insulting him.

Still, Rimuru accepted her reasoning.

After all, even Veela in Harry Potter could use their own hair to make wands. He... should be able to do the same, right?

The worlds were different, but it was also true that many of the Nasuverse's top-grade materials came from the bodies of Phantasmal Species.

Thanks to his ability to split apart, Rimuru could easily divide his body while keeping it alive. But that brought another problem: although he could strengthen a finished Mystic Code, changing its fundamental nature was incredibly difficult.

It was practically the same as starting over and scrapping all the previous designs.

Today marked Rimuru's 284th failure, and a week had already slipped by without him noticing.

"Whew. Researching Magecraft really can be incredibly absorbing sometimes."

The Wuyin Bird on his shoulder flapped off. Rimuru left the room and stepped onto the balcony, contentedly narrowing his eyes—

As he watched the bird, he found himself lost in thought.

Unlike his predecessor, who, after having his memories sealed, dreamed up the idea of turning Wuyin into a Mystic Code that could transform into anything, he was more practical—and even more ambitious.

Knowing all about the absurd Noble Phantasms in the story and the strange, wonderful objects in other works of fiction made it easier for him to understand what kind of Mystic Code he wanted, and gave him a better sense of how to make it.

It needed potential and enough power, and it had to be his own personal weapon—one that could grow.

"Water has no fixed shape, yet it can transform into anything... and contain everything."

Rimuru chuckled softly and murmured, "My predecessor's vision was still too limited."

He could devour corpses and steal other people's talents, so naturally his weapon should be able to devour other weapons and steal their abilities—even their forms!

For that reason, he had even studied Projection Magecraft and a magecraft for stealing things, but neither had gotten him very far. Considering that Emiya Shirou's Projection Magecraft could reach such heights only with his Origin, "Sword," backing it, Rimuru had asked the Great Sage about his own Origin without hesitation.

Just as he had expected, although the Great Sage's All of Creation couldn't break through the mystery of Akasha, it could give him a rough idea of his Origin. After all, the two talents that influenced him most were Predator and the Great Sage. With the Great Sage's help, he ran simulations and performed various tests, and he could all but confirm that his Origin was related to devouring, plundering, or predation.

That only strengthened Rimuru's ambition.

Research never yielded results overnight, and the difficulties would be overcome sooner or later. Over the course of a week, Rimuru had steadily worked through the problems, strengthening Wuyin as he went. At last, he had solved the issues of merging in new materials and converting its abilities. Success was only one step away.

Then he reached the most difficult part.

Rimuru couldn't keep the portion of the material fused with Wuyin alive for long.

Because of its properties, a piece of his body split off from him was like a divided cell. It could stay alive and even remain connected to his consciousness. But once it was treated as material and incorporated into a Mystic Code, that was no different from killing it to cook a meal—

That meant Rimuru couldn't keep Wuyin active for long. Predator's nature was to devour and digest enemies, then analyze their essence so it could simulate and evolve.

Wuyin had inherited that trait, too. It had to remain alive to digest and analyze what it devoured. Then the Great Sage, acting as its core, could reorganize its magic energy and transform it into the weapon it had consumed.

It might have been a bit of a shortcut, but in the short term, this was the only way Rimuru could modify the weapon. It also ensured that Wuyin would become his personal Mystic Code: without the Great Sage, it would be just as useless as Wuyin had been at the beginning.

"Wuyin Water's magic-energy limit and mystery are still too low. It can't support a split-off piece of my body supplied with magic energy."

Rimuru stared at the water bird. He seemed to be talking to himself, but was actually speaking to the Great Sage. "But if we use another material, we'll lose the effect of water having no fixed form."

"What a pain... Is this really the highest-grade Wuyin Water?"

"It's so weak."

"..."

The Great Sage fell silent for a moment. As a self-learning artificial idiot, a week of independent study had transformed her from a system that only gave notifications and stiff, mechanical responses into the personality Rimuru remembered: one that could crack jokes and think through human logic.

"Perhaps we could approach it from another angle."

"Hm?"

The blue-haired blob, basking in the sunlight with his eyes comfortably narrowed, blinked in surprise and came back to himself. "What angle?"

"Wuyin Water's material limitations mean that we have to adapt downward. So why not consider doing the reverse?"

"Couldn't we use your body as the primary material and make it compatible with Wuyin Water?"

"..."

Rimuru's first thought was that it was impossible. But he soon realized that it wasn't.

"Though, if we do that, you'll have to make it all over again—"

"There's no need to go to that much trouble."

Rimuru gave a mental command and called the Wuyin Bird back. He slowly brought it in front of him—

Chomp!

The crisp, sweet liquid burst in his mouth. Rimuru swallowed it in one gulp and said, "Analyze it, Great Sage."

Aside from being able to store things in his stomach, Rimuru vaguely remembered that the original story had given the Slime King another ability.

A real 3D Printer!

As long as he had the materials, he could use the analysis in his stomach to endlessly duplicate anything he had already devoured.

When Liddell led a little girl of about five or six to the door of Rimuru's room, she bent down slightly and gave her another very stern reminder. "Eler, when you meet Professor Rimuru, make sure to behave. Greet him politely, okay?"

"Mhm, mhm, mhm!" The white-haired little girl called Eler blinked her big eyes and nodded quickly. The cowlick on top of her head bobbed slightly, and she looked perfectly well-behaved.

But Liddell knew just how wild a little demon lord lurked beneath that adorable, well-behaved face. If she had to describe her, she'd say Eler was the sort who set fire to mountains and did every other kind of evil. If her teacher hadn't been able to keep a bit of a handle on her, the whole Achelotte estate might already have been blown sky-high.

Liddell still remembered how grateful and choked up the servants had been when she took the little girl off their hands—

Well, she wondered whether making this little terror Rimuru's student was really a good idea...

Liddell hesitated. But to be fair, Eler's aptitude for water was absurdly good. Add her Witch bloodline to that, and if nothing went wrong, she was sure to become a Color Rank Magecraft user in the future—

Just as Liddell straightened up and prepared to knock, she heard an excited shout from inside!

"Haha! It worked!!"

The hell? Even commas get censored now?

I'm coming clean: I'm not hiding it anymore. I'm the owner of Soul Materialization—Rimuru!

Rimuru was thrilled to discover that after directly analyzing Wuyin's structure, he could devour some Wuyin Water and make it inside his body as a split-off piece. Not only did this perfectly solve the problem of keeping it alive, but it also kept Wuyin permanently alive and connected to his body.

In other words, Wuyin could become part of his body and stay hidden inside him normally.

However, because the material had been replaced, the once-clear, transparent mass of water had turned into a pale blue blob resembling jelly. Its flowing, cool feel had also become springy and chewy.

At a glance, Wuyin now looked no different from one of his usual split-off pieces. But it truly had gained the ability to transform into countless forms. And with its connection to his body, whether Rimuru devoured a weapon himself or Wuyin ate one, he could use magic energy to simulate it. That meant he could continuously transform Wuyin into any weapon or Mystic Code it had already analyzed.

"Hmm... Though Wuyin is now a little different from a Mystic Code, the Holy Grail can attach itself to someone else's body, too. I guess it's not that strange."

Just as Rimuru was thinking this over after his excitement had settled, there was a knock at the door. After nearly a week of Rimuru's patient instruction, Liddell had finally learned to knock.

Though... she had only learned to knock.

Rimuru hadn't even had time to say "Come in" when the door swung open with a click. The proud pink-haired girl walked in with her arms folded, a serious look on her delicate face.

"Liddell?" Rimuru turned and set the blob he'd been testing aside. He wondered whether she needed something, but then a cute little head cautiously peeked out from behind the door. A cowlick of white hair bobbed from the movement, and a pair of big, adorable eyes met Rimuru's in a sudden stare.

Eler had been nervous about facing her strict teacher. After all, whenever she had managed to drive another old man away, she'd been punished with confinement and a lecture. But the moment she saw Rimuru, her eyes lit up!

What a pretty big sister!

Before Rimuru knew it, the white-haired little blob—half his height and ridiculously tiny—came rushing in and threw herself into his arms. "Teacher!!"

"Huh?" Feeling the little head nuzzling into his chest, Rimuru was utterly bewildered.

"Liddell?"

He turned to look at the pink-haired girl in confusion. She looked just as exasperated as she grabbed Eler by the ear and pulled her out of his arms. "What did I tell you? Bow first, then call him Teacher!"

"..." Rimuru was speechless. Wasn't she still... calling him Teacher?

Ten minutes later, Rimuru watched the little thing playing happily nearby with Wuyin, which had turned into a giant hamster half her size. He turned around with a pained look. "So, this is the student you wanted to introduce to me?"

"You're a professor, so you're bound to take students, right?" Liddell explained with a smile. There was affection in her gaze as she looked at Eler. "She's my teacher's direct descendant, so her talent is definitely nothing to worry about—"

"Taking students is one thing... but professors only take students because they need a few assistants for their research." Rimuru eyed Eler skeptically. "Can she really be an assistant?"

"You'll still need a personal disciple, right?" Liddell had barely finished speaking when the little girl lifted her head with a pitiful, adorable look. "Teacher doesn't like me...?"

"Uh..."

Rimuru paused. Well, he had to admit... she was pretty adorable?!

"Fine, fine." Rimuru sighed. If he had to be a babysitter, then so be it. He understood what the first Witch of House Achelotte was thinking: she simply wanted to deepen their relationship.

Perhaps House Achelotte had initially agreed to shelter him because the Tempest Family had offered them too much. But by now, Liddell and Rimuru had grown close, and the two sides had practically become inseparable. Now that he had begun his rise, it was only natural for House Achelotte to try to draw closer to him.

From the way Liddell doted on the little girl, it was clear that she really did like her. He could look after her junior as a favor to Liddell.

After all, Liddell had done a lot for him. Besides, Eler was only a little over five—not quite six. In any case, it was usually best to wait until around eight before starting formal instruction in systematic Magecraft. Well, Witch blood or not, she could at most be introduced to Magecraft a little earlier.

"Besides that, there's news from the Far East you were asking about."

"Oh?"

Rimuru had been watching Eler wrestle with the giant hamster Wuyin had become. Liddell's words caught his attention. "What news?"

On the streets of Fuyuki City, an autumn leaf was swept into the air by the swirling exhaust of a passing car. A fashionable young woman, dressed entirely in black with a cape draped over her shoulders, slowly set foot in the city.

Beside her, Aozaki Aoko—pulling a suitcase and brimming with youthful energy—curiously looked around at the scenery. Fuyuki City was one of the few well-known cities in the Far East with an established Magecraft family.

It wasn't as famous as the Aozaki Family, but the Tohsaka Family's Jewel Magecraft was still one of the few first-rate branches of Magecraft.

But Aozaki Aoko was obviously more curious about something else. "Wow, a three-hour trip. This is the farthest you've traveled since moving to Japan, isn't it, Alice?"

"Who could possibly be important enough to make you care this much?" She leaned her head over her indifferent friend's shoulder with an inquisitive look and teased, "You even called me back for this?"

"..." Kuonji Alice quietly turned her face toward her curious friend. After a moment of silence, she suddenly asked in a cool voice, "How long has it been since you last went to the Clock Tower?"

"...Two years, I guess." Aozaki Aoko blinked and gripped her suitcase. "I haven't dared to go abroad since the Director kicked me out last time. Haha..."

"I blew up quite a few things, mostly..."

"Then we'll go again in a few days," Kuonji Alice said softly.

"Huh?" Aozaki Aoko froze, her face falling at once. "No way! The Director already warned me last time... If I go again, they'll give me a Sealing Designation!!"

"Can a Magician even be given a Sealing Designation?"

"Wow!! You have no idea how scary that Director is!!" Aozaki Aoko said, looking aggrieved. "Anyway, I'm not going! Touko might be waiting for a chance to laugh at me!"

"Ultimately, you're the one who blew things up," Kuonji Alice said calmly, looking at her friend. "I'll go with you this time."

"?!!!"

"You're going to the Clock Tower?"

Aozaki Aoko blinked in disbelief. "Did I hear that right, Alice?!"

As her close friend, she knew very well how much Kuonji Alice hated the UK these days.

Kuonji Alice silently nodded, then said nothing more. She didn't like explaining herself.

Watching her silent friend, Aozaki Aoko suddenly understood.

Something must have happened at the Clock Tower, and it probably had something to do with Liddell and that jerk. Thinking of Rimuru made Aozaki Aoko grit her teeth in frustration. She and Rimuru had never gotten along particularly well. Compared to Aozaki Aoko's kindness, Rimuru's past methods had seemed cold, ruthless, and unscrupulous!

He was even worse than Kuonji Alice! Alice was merely stubborn about upholding the traditions of Magecraft, while that guy... simply had a terrible way of doing things!

A huge problem!

Worst of all, last time she had gone to the Clock Tower, she'd gotten curious and tried to look at that jerk's timeline. The timeline had gone haywire, causing a massive explosion. Ever since then, she'd been banned from the Clock Tower, and people had dubbed her the [Human Missile Launcher].

At the thought, her head began to ache. "You're really going, aren't you? Honestly, Alice, I think you're even more likely than me to get a Sealing Designation..."

"..." Kuonji Alice stopped and turned to stare quietly at Aoko...

"All right, all right! We'll go! I'll go, okay?!"

Aoko gave up resisting. She should have known better. The stubborn Witch was usually taciturn, but once she'd made up her mind... not even eight oxen could drag her away from it...

This was too much!

"Hmm..." Rimuru thought for a moment. "So you asked Alice, and she chose to make a preliminary visit... right?"