Around the time an innocent young boy transformed into a yuri monster…

Terukami Mizuhi, the girl farthest from perversion in Fectom Academy, had come to conquer a dungeon alone.

Holding her Dive Gear in one hand, with Nakayoshi! Dungeon-kun No. 6 activated, she wandered aimlessly. The Special Zone remained a desolate wasteland, and the surrounding school buildings—more like observation towers—shimmered in the early summer heat haze.

“…Can the sun be incinerated?”

Mizuhi glared at the sun reigning at the center of the blue sky. The heat was becoming increasingly unbearable.

Until now, Fectom Academy had never had something as luxurious as air conditioning, but this year, an excellent mechanic was supposedly planning to install it in every room. When she heard that, Mizuhi was so moved she nearly cried—something she hadn’t done since childhood.

“I hope the AC is finished today… I think they said they were going to inspect the invention together or something.”

Mizuhi was slightly mistaken.

Right now, what was happening at Fectom Academy was a meeting to recreate the unnamed tools from Miyume’s memories. And, preceding the Hinotsuchi Cultural Festival, a Hobby Exhibition had been held.

“Eating ice cream in an air-conditioned room… Hah, can such supreme bliss truly exist?!”

As she lost herself in this nonexistent future, even considering buying ice cream for everyone, an emergency alert blared from her Dive Gear.

“An urgent rescue request?”

Mizuhi stopped in her tracks at the priority-distributed distress signal.

The location was suspiciously close—as if someone had been waiting for her to arrive.

(Is this fate, too?)

With a faint smile, Mizuhi wreathed her legs in flames. Then, with a burst of scorching heat and shockwaves, she vanished from the spot.

■

In the highest floor of Arianrod, within the room where the Dungeon Cores’ radiance was observed, The Chairman stood alone, gazing at the ceiling.

The dazzling Dungeon Cores shone like stars—each one born from destruction.

The Chairman stared at them intently, as if engraving their light into his mind. Then, a girl appeared beside him.

No sound, no shadow—no, there hadn’t even been a sign of her approach. Or perhaps, she had been there all along.

The girl, with her short silver hair neatly trimmed, handed The Chairman a smartphone. The screen was cracked at the edges, its case partially chipped, and a cute charm dangled from it.

“A call for you, Master.”
“Ah, thank you, Solfi.”

The girl called Solfi bowed and took a step back. Pressing the phone to his ear, The Chairman spoke with a calm expression.

“Well, it’s been a while since we last spoke— ‘SORRY, CHAIRMAAAAN!!!’ —Hah, good to hear you’re as lively as ever.”

The apology was so loud it felt like his eardrums had been shredded. The Chairman winced momentarily but quickly smiled again, appreciating the energy.

“An apology right off the bat? That’s unlike you. You usually ask about your juniors first.”
“I wanna ask about them too! But this is a real emergency right now—! …Hey, Gardener-kun, back up! You can’t fight on your own!”

Amid the girl’s voice, explosions and shattering sounds echoed from the other end. Occasionally, the wet splatter of something bursting made the scene unnervingly vivid.

“Wait, what was I saying again?”
“You haven’t told me anything yet.”
“Oh, right! Then I’ll keep it short—yesterday, the Professor stole a bunch of angels! And now, a whole swarm of them is invading the academy, so I couldn’t report it until now!”

With just those words, The Chairman grasped the situation.

“…I see.”
“Me and Gardener-kun tried to stop the Professor, but it’s hopeless, yeah. I killed like two hundred already. It’s meaningless.”
“No, don’t worry. We’ll handle it here. Honestly, the fact that you killed two hundred of that Professor is impressive.”
“Really? Well, if you’re not mad, then great!”

The girl’s cheerful voice was followed by the sound of something collapsing in the background.

But The Chairman paid it no mind and continued.

“What about the Calamity? I thought you’d contact me about that.”
“Ah, that’s fine. It’s heading your way without issues. At this rate… day after tomorrow, maybe?”
“Day after tomorrow, huh…”
“Eh, is that a problem? Want me to just quickly deal with it here? I can toss the corpses over afterward.”
“No, it’s fine. In fact, if you kill it there, the laws of destruction might collapse. Just stick to the plan. …Though, that day coincides with the territory battle between Kisou Academy and Mikage Academy.”
“Eh, they’re fighting!? I wanted to see that—!”

The imminent territory battle.

It seemed this turning point in history—one that would be talked about for years—would arrive soon.

(This can’t be a coincidence. The Professor must be planning something for that day.)

“…Hey, you’re overthinking again, aren’t you? You really gotta stop that.”
“Hahaha, you’re right. I was just looking forward to the territory battle.”
“You’re way too carefree… Ah, more angels incoming. Chairman, I’m hanging up. Gotta go slaughter another wave. …Hey, Gardener-kun, wake up. …No, turning into a girl won’t help. Actually, stop changing genders so much—it’s creepy—”

The call ended amidst the lively chaos.

The Chairman looked at the now-dark screen with an amused expression before turning to Solfi.

“Should we record the territory battle and send it to her?”
“I’ll arrange it.”
“Thank you. I’ll leave it to you, then.”

Returning the phone to Solfi, The Chairman resumed gazing at the Dungeon Cores’ glow. Then, he suddenly muttered, “Ah.”

“I should’ve told her my junior is participating too.”

■

The emergency rescue request sent to Terukami Mizuhi led her to a surprisingly simple dungeon interior.

“…What is this?”

A room enclosed by gray walls. At its center lay the student who had presumably sent the distress signal—collapsed on the ground.

A pool of blood had formed around the girl, who was face-down.

“Tch—are you okay?!”

Mizuhi rushed over and immediately engulfed the girl in flames.

Then—

“—!?”

The girl burst apart.

White feathers scattered as laughter echoed from nowhere.

Mizuhi realized—she had been lured into a trap.

“Is this… one of Kei-nee’s ‘troublesome fans’?”

(No one was around to correct her.)

Fortunately, Kei-nee had taught her: “If troublesome fans go too far, you can beat them to a pulp.”

Mizuhi promptly drew her twin pistols and stood still.

After a few seconds, the room’s corners twisted, and something lunged out.

“Too slow.”

She shot and incinerated it instantly.

As if that were the signal, more creatures began pouring from every corner of the room.

Mizuhi burned them methodically while observing.

(Birds…?)

They were birds—but unsettlingly, every one of them was flawed.

Some had twisted legs, others split beaks, and some even had torn wings.

These birds, seemingly designed with such distortions rather than injured, relentlessly swarmed Mizuhi. Yet, not a single one could even touch her.

“How petty.”

She aimed her guns at the floor and pulled the trigger.

Flames spread across the ground, walls, and ceiling—igniting the dungeon itself.

“How dull. Bring something more entertaining next time.”

By the time Mizuhi spoke those words, the dungeon had already dissolved, leaving only the Special Zone behind. The magical energy sustaining it had been erased.

“…Hm? The ‘troublesome fan’ isn’t here.”

She had expected the culprit to appear once the dungeon burned away. Tilting her head, she then noticed something else.

“Where’s the Dungeon Core? I made sure to leave it intact.”

A Dungeon Core was essential for constructing a dungeon. Typically, it was embedded within the dungeon master, though occasionally it existed separately. Either way, it always remained as a physical object afterward.

But not this time.

A trap set specifically for Mizuhi, grotesque monsters, and now a missing Dungeon Core.

Something was clearly wrong.

Mizuhi stared at where the dungeon gate had been, deep in thought. But with so little information, she couldn’t piece anything together.

Just as she was stuck, a notification chimed.

“Hm?”

Activating her Dive Gear, she saw a message from Toa. Curious, she opened it.

A single photo expanded on the screen—a group picture, seemingly taken just moments ago.

But two unfamiliar faces stood out.

“…This must be the Jingūji heir Miroku mentioned.”

The boy was easy to place. Miroku had mentioned corporate visitors arriving today.

Mizuhi scrutinized him before nodding approvingly.

“For his age, he has remarkably sharp eyes.”

She liked the boy’s gaze—innocent yet filled with resolve. If he wished, she might even train him.

Then, her eyes shifted to the other stranger—a beautiful girl in a pure white dress, with long black hair.

Unlike a carefully cultivated flower, she resembled a wild blossom by the roadside—modest and pure.

In the photo, she stood in the center, smiling shyly.

“Who’s this…?”

Mizuhi was baffled.

She pondered, deliberated, and then—

“I should buy more ice cream.”

She arrived at the most logical conclusion: increasing the ice cream order.

The bizarre events from earlier had already vanished from her mind.