“Whew… done! Another success today!”

Nia Bella, the witch who successfully conjured a small flame, smiled brightly.
She now had something to tell her big sister again.

She felt proud of her steadily improving magical abilities and deeply grateful to the one who had believed in her and brought her into the party.
She felt as though she owed her an eternal debt of gratitude.

“The Fire Giant, right?”

She remembered the enormous Fire Giant that had appeared while she was unconscious, the result of her own magic running wild.
Yet, Nia Bella was currently unable to summon such a creature.

“I’ll surpass that version of myself.”

And one day, she vowed to create magic far more powerful than that Fire Giant.
Something that would make her mentor and benefactor—her sister—feel proud of her.

“…Alright!”

With newfound determination, Nia Bella resumed her magical training, taking her stance.

At that moment, the ground shook.

“Huh…?”

Nia Bella, who had been crouching in one corner of the mansion’s garden, slowly stood up and looked around.
She noticed something rising from the mountains in the north.

“…What is that?”

It was something so massive that it could easily eclipse the Fire Giant she had once summoned.
The air was thick with demonic energy emanating from that colossal presence.

“Could it be… a monster?”

Was something like that really a monster?

“Nia Bella!”

At that moment, one of the mansion’s servants came running, out of breath.
The servant, who had always remained composed, now had a face drenched in sweat from the rush.

“The gate! The gate!”

“C-Calm down! What’s going on?”

“A huge number of monsters are gathering at the mansion’s front gate!!”

Hearing this, Nia Bella followed the servant toward the front gate.

“Block them!”

“Hold the formation! If we falter, they’ll break through!”

There, the guards were confronting long, cylindrical monsters.

“Raul!”

With a short chant, Nia Bella sent flames rushing toward the monsters that were threatening the guards, burning them to ashes in an instant.

“Thank you… Thank you so much…”

“It’s fine… Are you okay…?”

That was when Nia Bella noticed something strange about the monsters.
They seemed oddly familiar, as if they resembled the massive creature she had seen rising from the mountains earlier—only these were about half the size of a human.

‘What in the world is happening…?’

“Nia Bella, where is the Hero?!”

The Hero.
Of all times, he had gone outside the city to complete a request.
Even if he turned back right away, it would still take him quite some time to return.

“Nia Bella, if possible, please give us orders…”

“…”

The Marquis of Rakru had descended to the city below.
All eyes—from the servants to the guards—turned to Nia Bella.

She was deeply confused and frightened.
But she was a member of the Hero’s party.

‘Sister. Leave the mansion to me.’

“…Let’s start by sealing the front gate.”

Summoning her courage, Nia Bella began to direct the people around her.

“Hurry and evacuate the citizens into the church!”

At Saint Aria’s command, the priests swiftly moved people to safety.
Meanwhile, a monster lunged at Aria.

A worm-like creature, the size of a human, aimed for her neck, but an arrow struck it down, tearing it apart.

“Aria, what’s the situation?”

“It’s bad! We don’t even know where the monsters are coming from…!”

Lafirie clicked her tongue.

This situation was worse than the one in Alpareth.
On a battlefield where civilians and monsters were mixed, those with more to protect suffered greater losses.

And now, the people with the most to protect were the citizens of this city, led by the Hero’s party.

“…Can you cast a protective barrier?”

“Yes, I can!”

“I’ll gather the mercenaries and rescue the citizens. Once I send them to you, protect them.”

“Got it!”

“Do you know where Serlyn and Louis are?”

“Lady Serlyn is probably at the guards’ headquarters! As for Lady Louis… oh no.”

Aria’s face turned pale.

“She’s… working at the mine.”

“What…?”

Lafirie’s head snapped toward the mine, where the massive monster had appeared.

Then that meant Louis was…

“…Louis is strong. She’ll be fine.”

Lafirie strung her bow with a green-glowing arrow as she spoke.

“Once I find Serlyn, I’ll tell her to look for Louis. For now, let’s focus on evacuating the citizens.”

Fortunately, the giant monster had made no further movements since it appeared.
Taking advantage of that, they had to evacuate as many people as possible out of the monster’s reach.

Lafirie’s green eyes gleamed, reflecting her firm resolve.

Boom!

“Argh!”

“Guards, scatter! Focus on evacuating the civilians in the area!”

Serlyn shouted orders as she glared at the giant insect monster clacking its mandibles in front of her.
The creature was several times the size of a human, as tall as a building.

It seemed to be a child or a smaller version of the giant monster that had emerged from the mine.

Screech!

Another one appeared.

Without hesitation, Serlyn leaped onto a nearby rooftop to get a better view of the situation.
She saw citizens screaming as yet another one of the giant monsters slithered in the distance.

‘Aswell.’

Of all times for him to be away, the entire Hero’s party was scattered.
Still, Serlyn knew that her companions were strong, and they were all fighting somewhere in the city.

They just had to hold out until the Hero returned.

With determination set on her face, Serlyn swung her sword again.

Mercadia Karacioni.

In the original story, there was never a point where she directly confronted the Hero’s party.

That’s because her role was to attack this world while the Hero’s party was in the demon realm.
In other words, her being here now was impossible.

So, how could I know about her?

It was thanks to information I received from someone after the story’s ending.

“Hmmm~. Hmm-hmm~.”

She hummed a tune from atop the giant worm-like Behirastok.

“Never make eye contact with that demon.”

The demonic energy she emitted was so powerful that an ordinary person’s body would melt just from being near her.

The only saving grace was that she hadn’t noticed our presence yet.

“Is there a shortcut to the city from here?”

“Yes. There’s one, though it hasn’t been used in a long time.”

“Please, take it to get back to the city.”

As I spoke, I cast enchantments on their weapons.
This way, even without me, they could at least protect themselves.

“Miss Louis, what about you…?”

“I have to stay here.”

“W-What?!”

“Let’s escape together…! If we run away, we can—!”

“That thing won’t just stay still. I need to buy time by facing it myself.”

Only the Hero could kill a duke-level demon like Mercadia.
The other party members and I could try, but it would take dozens of times more effort than if the Hero faced her directly.

So, the goal now was to hold out until the Hero returned.

“…Go now.”

“I’ll bring reinforcements as fast as I can…!”

“Be careful!”

With those words, the miners hurried toward the shortcut.
Now, I was the only one left in the mine.

“Are they gone?”

“…You knew all along, didn’t you?”

“Of course. How could I not notice your presence?”

Mercadia slowly turned her head toward me the moment the miners left.
She had known about me and the miners from the start.

But she had pretended not to notice, due to her personality.

“Aha~! Things are finally getting interesting. What’s your name?”

She was a demon who only respected the strong and avoided unnecessary conflict with the weak.

“Louis.”

“Louis…? Wait, Louis?”

She paused for a moment, then asked again. I gave a small nod in response.
At the same time, I took out the master key, preparing for the battle ahead.

“Are you the mage from the Hero’s party?”

How did she know about me?

I stayed silent, and her lips twisted into a wide grin.

“Aha! Aha-ha!! So, you’re the one who wiped out those vampires! Aha-ha-ha-ha!!”

Laughing so hard that tears welled up in her eyes, Mercadia finally caught her breath and spoke.

“Haah… Thanks to you, I was able to descend here. I guess I owe you a favor.”

Slash!

“Oh my.”

Mercadia vanished for a second, only to reappear behind me.
However, her strike was blocked by my shield.

“I expected that.”

I quickly turned around and aimed the tip of the master key at her.

Boom!

“Your magic is quite impressive.”

Mercadia nonchalantly deflected my attack, complimenting my skills with a gesture.
Meanwhile, the gigantic worm-like creature, Behirastok, began to move.

“Let’s see how long you can last against me. The time limit is until Behirastok destroys the city.”

If the mining city of Rakru were to fall, all our efforts to save it would be for nothing.

That couldn’t happen.

‘Honestly, didn’t you see this coming?’

No.

After possessing this body, I had considered countless possibilities and variables as a member of the Hero’s party.
One of those possibilities was encountering a demon duke in a form different from the original story.

So, in a way, I had anticipated something like this.

Still, if I let my emotions control me and failed to handle the situation, the responsibility would fall on me.

Which is why I would stop both of them.

‘I’m sorry, mentor.’

It wasn’t for Mercadia, but I had prepared something to face a demon duke.
Specifically, I had designed a fail-safe for one particular spell.

“Haa…”

Perhaps it was because the chaos had taken form in Mercadia, but my mind felt clearer now.
I felt like I could inscribe spells more accurately and cast magic more sharply.

“Mercadia.”

“…You know my name?”

“From now on, you and Behirastok won’t move from this spot.”

Because I was going to stop them.

I pulled out the card I had prepared for this moment.

“Master key. Shape-shift. Form two.”

Click.

With that, the two rings on the master key began spinning violently, transforming the entire staff into a new form.