Chapter 36

After walking for a while, we finally reached the room.

"What is that...?"

Inside the spacious room with a bronze door, a giant snake was coiled up.

The snake had a trunk as thick as a large tree and black scales. However, its upper body was that of a human. The skin and arms were human-like, black like the scales, but the head was that of a snake. It was a bizarre creature, like a deity worshipped by a cult.

In its crossed arms, it held a massive sword, but the snake's eyes were closed.

Is it sleeping...?

"That's a Naga," Amu said, peering through the gap in the door.

"I've never seen one before. It's probably the boss of this dungeon."

"Boss?"

"The core of the dungeon or a monster guarding the core."

"I see."

So, defeating that thing would mean clearing the dungeon.

"By the way, will a path to the outside appear if we defeat the boss?"

"In a dungeon that goes deeper, that's impossible. But this place has been flat all along, and it feels like it's based on a ruin... so maybe. There seems to be a passage at the back of the room too."

"Alright, then..."

"But I think we should give up."

Amu interrupted.

"Why?"

"The Naga is a formidable enemy. For a six-person party, everyone needs to be at least level four, and for a four-person party, at least level three. Besides, I've never heard of a black Naga. They're usually sandy-colored, and the red ones can breathe fire, so this one probably has some special ability. It's too dangerous not to know what it is."

"..."

"Let's turn back. There should be another entrance, so it's safer to look for that."

"I can't do that, Amu. We don't have the time or preparation to explore. We should consider it lucky that we reached this room while we still have energy."

"..."

"Let's defeat it. Even if there's no exit beyond this room, destroying the core will eliminate the threat of monsters."

"Seika... do you have confidence in defeating it?"

"With Amu, I do."

Amu lowered her eyes and smiled softly.

"Alright. But if it looks bad, we should run. Got it?"

"I'm good at running too. Just tell me when to retreat."

Indeed, running is always an option.

Amu drew her staff-sword from its sheath.

"I'll count to three. Once we're in the room, the Naga should wake up, so cast your spell before it gets ready."

"Got it."

Might as well do it properly with the incantation and gesture.

"Three, two—"

I visualized the form.

"One!"

Amu kicked the door open and dashed in.

The Naga's snake eyes slowly opened, and it turned its gaze to Amu, who was holding the sword in both arms.

*Wood Aspect—Pile Driving Spell*

Logs like ash stakes were launched, knocking the sword out of the Naga's left hand.

Two more stakes hit its chest and torso, causing it to stagger. Indeed, the power is different when done properly. However,

"...It's not deep enough."

The stakes didn't deal much damage. The Naga pulled them out with its left arm and turned its elongated pupils toward me.

"Don't get distracted!"

Amu fired a fireball at the Naga's head, causing it to stagger. She deflected the massive sword with her incredible strength and continued to harass it with magic.

Oh, this gives me an opening.

*Wood Aspect—Pile Driving Spell*

I launched thick stakes at the Naga, which was distracted by Amu. They pierced its shoulder and throat, dealing significant damage this time.

I see. This is the role of a tank. Thanks to Amu drawing its attention, I can cast spells more easily during the battle. In my past life, warriors and mages working together made demon hunting easier, didn't they...?

"Be careful! Something's coming!"

I saw the Naga inflate its chest.

It leaned forward and spewed a liquid from its snake mouth.

Amu rolled to avoid it, and I retreated to dodge. The liquid on the floor bubbled and dissolved.

It spits strong acid.

Wow...

The sword was swung down at Amu, who was off-balance, but an ash stake deflected it. The Naga turned to me, but Amu's wind magic held it back.

"Amu, I want to move forward a bit. Can you take the attack?"

"O-Okay!"

I supported Amu with *Pile Driving* while looking for an opportunity.

Not yet, not yet...

When Amu's magic made the Naga stagger, its chest inflated again.

The prelude to spitting acid.

This is it.

*Gold Aspect—Exploding Nail Spell*

A white metal spear pierced the Naga's mouth as it spewed acid. The acid melted the spear and the upper body, and the Naga let out a silent scream, writhing in pain.

"Fall back!"

I signaled Amu and tried to cast *Ghost Fire*, but the thrashing tail blocked me.

No good, it's on full alert...

Wait, I don't have to do it myself.

"Amu! Aim for the head with a fireball!"

I called out to Amu, who was in a good position. She responded with a fireball spell, which flew accurately at the Naga's head—,

A spectacular explosion erupted from the spear.

The half-human, half-snake monster thrashed wildly on the ground, defenseless.

"Finally, it's lowering its head."

And into the still burning eye socket of the snake head—Amu's staff-sword was deeply thrust.

The human upper body and snake lower body convulsed violently.

But eventually... the dungeon boss, the Naga, stopped all its movements.

The flow of power suddenly weakened and disappeared.

It seems to be dead.

Phew, it ended more easily than I thought.

"Amu! We did it—ouch!"

"Seika!"

Amu ran over and hugged me.

"We did it! Haha, this is my first time defeating a dungeon boss! We just formed a party, and we're already in sync, aren't we?"

Amu grabbed my hand and jumped around excitedly. Her carefree smile—she really reminded me of that girl. Just a few years before my reincarnation, she used to laugh like this in my mansion.

However, I was certain from the process.

Amu has no relation to that girl.

When we first met, I wondered if she had followed me after reincarnating. But that's technically impossible. No matter how much that girl wanted to, she couldn't find my soul among countless other worlds and reincarnate on purpose.

Moreover, the flow of power was different, and she showed no signs of having memories. Most importantly... given her personality, I couldn't imagine her chasing after me.

Just a coincidence. It's not rare. Just like how that girl and my sister had no blood relation at all.

That life in that world is over.

The world isn't so convenient that you can talk to someone you left behind.

"Huff...! Uh, ahem."

Noticing my warm gaze, Amu suddenly came to her senses, blushed, and coughed, letting go of my hand.

I chuckled and said,

"But you were reckless, you know. You didn't have to go for the finishing blow on something that was thrashing around like that."

"Well, some of them can regenerate if you hesitate. I made sure to finish it off, so it's fine."

"Yeah, you're amazing, Amu. Not many people can do that."

It reminded me of the warriors in Japan who could cut demons with human-like prowess.

While stroking her red hair, I thought about these things, and Amu gave me a suspicious look.

"What's with your hand?"

"Ah, sorry."

I quickly removed my hand from Amu's head. I sometimes do this to Eifa too, but it makes me feel like I'm treating her like a disciple. She might not like being treated like a child, so I'll stop.

Amu turned away.

"...It's fine, though."

"Huh? What?"

"Nothing. Anyway... what's that silver spear? It exploded with fire magic."

"That's a metal with explosive properties."

Discovered by alchemists in ancient Greece, the silver of Magnesia has the unique property of burning on its own. It also easily dissolves in acid, releasing a flammable gas, making it easy to cause an explosion with *Exploding Nail*.

It was perfect since it was spitting acid.

"Are you hurt?"

"...No. Unnaturally so. I thought I'd get a minor burn."

"That's probably because the talisman I gave you acted as a substitute. It should still hold up."

"Really? Talismans are so convenient."

"It can't heal major injuries, though. Shall we move on?"

As we started walking, I looked up at the ceiling.

"If there's an exit ahead, it should be near the temple."

"...? How do you know that?"

"Ah, just a hunch..."

I quickly tried to cover up my suspicious answer.

Yuki whispered in my ear.

"Seika-sama, do you know where we are?"

"Yeah, I've known for a while."

"How...?"

"Using a spell to detect magnetic forces."

The magnetic force of a magnet can influence through thick layers of earth, one of the few forces that can do so. By creating a strong magnetic field with yang energy, it can reach the surface even from a distance. I detected it with a spirit in the form of a bee.

Bees have minerals in their abdomens that react to magnetic fields, allowing them to sense changes. While the spirit doesn't have such minerals, it functions the same by following the specimen. By changing the position and height of the magnetic field and detecting it from the ground, I could determine our approximate location.

Foxes and pigeons could have done the same, but bees were the best for detecting small changes near the surface.

It was hard to see, though.

"Then, could you have escaped at any time with the exchange spell?"

"Yeah."

"Then why... why did you go through all this trouble?"

"I told you, I wanted to enjoy it. It was my first time in a dungeon."

Also, I wanted Amu to gain experience.

—To eventually become the strongest.

*Exploding Nail Spell*

A spell that launches a spear made of magnesium. Magnesium not only burns on its own but also easily dissolves in acid and even warm water, releasing hydrogen. Although it was discovered in modern times, in the story's world, it was separated from a mineral called talc by ancient Greek alchemists.

*Magnetic Stream Cloud Spell* (not mentioned in the story)

A spell that creates a strong magnetic field around the human form using yang energy. Originally used to deflect arrows using Lenz's law, Seika used it as a beacon to determine his location from the ground.

*Shikigami (Bee)*

Bees can sense magnetic field changes due to magnetic crystals in their abdomens. They likely developed this to communicate the location of nectar to their hive. They can also see ultraviolet light.