Late July—the height of summer, when the heat is at its cruelest.

Outside, the air itself seems to shimmer and warp; a basin of cold water left in the sun will turn to steam in under thirty seconds.

No one with a choice willingly steps out under such a furnace sky.

“Phew… finally home.”

Dumping his heavy travel bag, an utterly ordinary-looking boy—Itsuka Shidou—slapped the air-conditioner on, then collapsed onto the sofa still slick with sweat, too drained even to groan properly.

“Pathetic. It was only a school trip. Are you really this exhausted, you spineless, good-for-nothing worm of a man?”

The scathing voice came from behind. A moment later twin crimson tails swam into view: his little sister, Itsuka Kotori, black ribbon tying back her hair, a Chupa-Chups lollipop rolling between her lips.

Shidou could only sigh at the familiar verbal abuse. When the ache in his limbs had eased a little he pushed himself upright and answered weakly, “If it had been an ordinary field-trip I might be fine, but… a lot happened.”

Half-way through the trip he had been dragooned by the Yamai Spirits—who’d just happened to cross paths with the group—into acting as judge for their “who-can-seduce-him-first” contest. While he was still agonising over which of them to pick, DEM’s strongest Wizard, Ellen Mira Mathers, had shown up intent on abducting Tohka. The Yamai twins, each realising the other secretly wanted her to survive, had exploded into a furious battle… In short, it had been a catastrophe from start to finish.

They had all survived, somehow, but for an ordinary high-school boy the accumulated fatigue—mental and physical—had caught up with him the instant he walked through his own front door.

“Well… you did have it rough. I thought the travel agency being a DEM front smelled fishy, but I never expected them to attack outright. Sorry I wasn’t there.”

Kotori bit her lip, the tips of her ribbons drooping in unison with her mood. Shidou gave a wry, fond smile and reached out to pat her head.

“Don’t say that. Knowing my little sister was worried about me is the best pick-me-up a guy could ask for!”

“B-baka! What embarrassing nonsense are you spouting? Who said I was worried?!”

Face scarlet, Kotori flailed; then, unable to meet her brother’s ever-kind grin, she jerked her head away. After a theatrical cough-cough she changed the subject.

“So, how’s Tohka? Any after-effects?”

Shidou obliged, pouring himself a glass of water. “She went back to the dorm to unpack. Seemed in a pretty good mood.”

“Figures. No emotional spikes on the monitors either.” Kotori exhaled, then grinned mischievously. “And the Yamai twins? How are my big brother’s newest beautiful Spirit conquests?”

Cough-cough! “Don’t phrase it so misleadingly!” Water went down the wrong pipe.

“My, my, I only spoke the truth.” Kotori’s smile turned triumphant.

Too tired to argue, Shidou sighed, clicked the TV on and answered, “Yuzuru and Kaguya were taken back by Reine for a routine check-up.”

“Huh. Got it.”

Though Kotori was commander of the airship Fraxinus, she had just returned from a round-table meeting at Ratatoskr HQ; her knowledge of recent events came only from brief written reports.

“Look, if you want details ask Reine. I’m grabbing a bath.”

Having recovered a little, Shidou couldn’t stand his sweat-soaked clothes a second longer and headed for the bathroom.

“Already filled the tub for you—I used it earlier,” the white-ribbon, ultra-sweet “imouto-mode” Kotori called in a syrupy voice, eyes still on the TV.

Touched, Shidou smiled and stepped inside.

(We interrupt our scheduled programming for a breaking-news flash: several days ago a vast thundercloud system suddenly appeared above the XXX desert region…)

Kotori’s eyes narrowed at the footage.

――――――――――――――Scene Change――――――――――――――

“Ahhh… resurrection.”

Clean at last, Shidou sank into the steaming tub, groaning like an old man. The bath-ball Kotori loved—Bub-brand bubble bath—had turned the water milky; he decided not to complain.

Staring through the steam at the ceiling, he let his mind drift.

An utterly average high-schooler who had somehow gained the power to seal the world’s “disaster spirits,” now spending his days trying to make those very spirits fall for him—together with his little sister and her eccentric crew.

Even after all this time it felt surreal, like a dream he might wake from any moment.

It wasn’t that they were beautiful girls and he wanted a harem; he simply never wanted to see a spirit like Tohka wear that lonely, sorrowful smile again. That resolve had set him on this road.

“Still… to the rest of the world I’m just a two-timing, heart-breaking playboy, huh…”

The rumours floating around school were enough to make him want to curl up and die.

“Better not think about it…”

With a self-mocking chuckle he stood, toweled off and started planning dinner.

(Shidou, can you hear me?)

The wireless earpiece—water-proof, left in for exactly these moments—carried Kotori’s voice.

“What is it, Kotori?”

She never used “onii-chan” when the black ribbon was on: pure commander-mode.

“Something’s come up. I’m aboard Fraxinus; get up here after you dress.”

Questions could wait; the note of urgency in her voice could not.

――――――――――――――Spatial Transition――――――――――――――

“What’s so urgent? No space-quake alarm has sounded.”

Dressed in casual clothes, Shidou stepped onto the bridge and walked toward Kotori’s command seat.

“Dense as ever, I see. When did you regress to single-cell status? Need me to jump up and down on your skull a few times to knock some neurons loose?”

“R-really, Commander?!”

Vice-commander Kanzaki Reine—tall, handsome, ever-eager—reacted before Shidou could, voice trembling with delight.

“Not you!”

Thud! Kotori’s fist buried itself in his solar plexus. Reine collapsed wearing an expression of pure bliss.

“…So, what did you want to show me?”

Trying hard not to admit he was already used to this spectacle, Shidou steered the conversation back on track.

“Shidou… watch this footage first.”

Murasame Reine—the ship’s analyst, his homeroom physics teacher, and a woman who looked one missed nap away from death—pointed at the main monitor.

A satellite image: a stretch of pale desert suddenly swallowed by pitch-black storm clouds. When the clouds dispersed, the land beneath had turned charcoal-black, as though someone had erased it from the world.

“Wha… what am I looking at?”

“A thundercloud—cumulonimbus. Surely even you’ve heard of lightning, Shidou?” Kotori needled.

The screen switched: pillars of black smoke, hills and cliffs coated in industrial slag, not a blade of grass, not an insect—an image of the day after the world ended.

“One week ago a storm front appeared out of nowhere above the XXX desert, scorched everything to cinders in minutes, then vanished just as fast,” Reine explained in her usual flat tone.

“That’s… impossible…”

Half-way through his protest Shidou fell silent, the single word slipping out: “…Spirit.”

“Ah, the light-bulb finally clicks. Good boy.” Kotori smirked.

Spirits were labelled “disasters” because of the spatial quakes they triggered—and the secondary calamities their powers could unleash. A phenomenon this unnatural screamed Spirit involvement.

“Luckily it struck an uninhabited desert. If a city had been underneath…”

She didn’t need to finish; the death-toll would have been measured before anyone could evacuate.

“What kind of Spirit could do this?”

“Hold on… I’m searching the database for lightning-type—”

“Oh? A lightning storm fierce enough to tear the world apart… could that be our dearest friend, the Thunder Miko?”

“Affirmative. No doubt remains—it is Liangyi Mengyue.”

Two bright, carefree voices cut across the tense bridge.

One belonged to a proud, long-haired girl who wore her locks like a crown—Yamai Kaguya.

The other, a languid beauty with a tri-braid—Yamai Yuzuru.

The twins Shidou had sealed during the school trip.

“Kaguya, Yuzuru… you know the Spirit who did this?”

Under the crew’s collective stare the sisters nodded in perfect sync.

“Of course. Before you, she was the very first friend we ever acknowledged.”

“Guarantee. That scorched earth bears the signature of our beloved comrade—Liangyi Mengyue.”

P.S. For some reason, after finishing this chapter I suddenly wanted to cut Shidou down. Calm yourself, my right arm… the seal is not to be broken yet…