“Whoa... the air’s thick with lightning essence, like wet ozone wrapping my face! And—hey—whoa! That was close!”

I step out toward the sixth floor’s passage and wobble. My stomach lurches first; then I look down. The ground is jagged like broken teeth on a cliff face.

One misstep and I plunge. I squint and admit it: this isn’t like a cliff. It is a cliff. The ledge is tiny, like a lone tile on a rooftop sea.

I can’t stride anywhere. I scan for a goat path down, any thread of trail stitching the rock.

“...”

Vertigo hits like a cold wave. It’s so high my eyes blur. Below, only smeared mountain chains, a forest like moss, and a churning sea of clouds.

The air’s thin, like a hollow reed in my lungs. No wonder my breathing’s been snagging. I can’t go down. I’m a touch acrophobic, and I don’t fly.

Rumble—rumble!

Thunder claws me out of my daze. I finally look around; before, I’d glued my gaze to my boots.

“This...!”

A canopy of black cloud blankets the sky, with lightning threading everywhere like silver snakes. It’s a world of thunder, a storm-wreathed realm without edges.

The constant peal rattles my bones. My scalp prickles, ants of static marching. Eek—there’s a bolt spearing straight for me!

Boom!

It smashes a few slabs of rock to gravel. I dodge, a leaf in a gale. But I can’t go far. This ledge is tiny—maybe a third of my Egisia Academy dorm.

The ground’s all ridges and pits, like dragon scales. Places I can step are scarce as coins in a beggar’s bowl.

Too close. I almost went over. I glance back and the abyss yanks at my gut again. If I stay, a slip is only a matter of time.

I need a safer perch. But all around is only lightning, like a rain of spears. No other peak, no gentler crown of rock. Only this cliff under my feet.

Another bolt. The ledge itself won’t last; it’s a candle stub in a storm.

“So I’m going to fall soon?! No—please no!”

Fear wells first, hot and tight. Falling from this height would end me. And the storm’s bite hits like SS-rank spells. I might not even leave bones.

I just cleared the gloomy Garden of Eternal Sleep, and now I’m tossed onto an even worse killing ground. Can’t there be a normal floor? Compared to this, the first four were paradise.

What do I do?! Panic spins me in circles, a trapped moth around a lamp. I can’t find a method, only misery. I toe a pebble and kick it into the dark.

“Don’t be so pessimistic, Yumigawa Sumeragi.”

As sudden as a blade of wind, FrostyLily Dream’s voice rings in my mind. My knees buckle, and I nearly go over the edge again.

“Hey! Don’t jump-scare me here! That’s lethal!”

I know it’s not her fault, but the complaint slips out like steam.

“That panicked face of yours never gets old. Shame you’re already taken.”

She swats away my protest and teases me instead, like a cat tapping a glass. I sigh. That’s her. Complaints are leaves in a river.

I breathe once, slow, and sort my mood. The question itching most comes first. “Lady FrostyLily Dream, what exactly is the sixth floor? Why can’t I find a way down?”

“Straight to it, huh? Fine. First, congrats on clearing the fifth floor on your looks alone.”

She chuckles, then turns brisk. “As for the sixth: your footing is only here. You can’t go down. You can’t leave.”

“I can’t leave this cliff?!”

Her words hit like ice water. How do I clear it then? You can’t even stand steady here, let alone fight. Watch—every few dozen seconds a bolt drops.

“Yes.”

Sensing my knot of doubts, FrostyLily Dream continues. “You don’t need to fight on the sixth... well, let me lay it out. It’s called the Cliff of Thunder.”

“As the name says, a cliff wrapped in countless lightning, like a brood of dragons in the clouds. The bolts range from S-rank up to the weakest Sacred Realm Novice. Tread carefully.”

“Mere lightning hitting Sacred Realm Novice power?! ...We’ll shelf that. What did you mean by ‘don’t need to fight’?”

The shock flares, then I seize the earlier line. No fighting—then how do I pass? Fulfill the guardian’s condition?

“Before I answer, let me ask you something. Ever heard of tower defense?”

“Tower defense...”

The phrase rings a bell, a page turning in memory. I sink into thought for a few heartbeats. Got it. I once read it in a book on games.

You protect a designated spot from being overrun. If it falls, you lose. So the Cliff of Thunder is cleared by playing tower defense?

“Right. Not exactly the same, but close. Simple terms: this cliff you’re on is your foothold.”

“To clear it, you protect your foothold from being destroyed within the time limit. If it breaks, your end isn’t ‘game over’. It’s body shattered, no bones left.”

Gulp. The condition sounds simple as a proverb, but the danger’s a knife under silk.

“To protect it... means enemies will try to break it. What kind of enemies?”

“Three waves in this trial. Keep your foothold intact until the clock runs out and you pass. The waves are—first, lightning itself.”

“Second, an assault by a lightning-aspected dragon. Third, the floor’s guardian.”

“I—”

I lean in for details, but her tone snaps taut. “Eh? My snacks! They’re about to burn!”

“Yumigawa Sumeragi, that’s the gist. I’ll cut the rest short. The Cliff of Thunder’s guardian is a lightning Dragon King at Divine Novice.”

“Hint: ‘Guard your foothold with everything you’ve got.’ That’s all. Good luck—ah, my snacks!”

Before I can reply, her voice and presence blow away like mist. I exhale. She said enough. Can’t wring the well dry.

“Looks like clearing the Cliff of Thunder’s going to be brutal.” I can’t help a wry smile, thin as a paper talisman in rain.