“Ah, what a nostalgic feeling. How long has it been since I stood here giving a lecture?”

Was this the first time since Tyr went berserk? After a brief moment of reflection, I tapped the blackboard with my chalk and began the lesson.

The Regressor, whom I had displaced from the lectern, looked rather disgruntled.

“Ninety days? How is that possible?”

“Now, now. Don't get ahead of yourself.”

Time to get to work for a change. I coated the tip of the chalk with alchemical light and tapped the blackboard.

The method of escaping the bottomless pit that I had read from Lieutenant General Ebon's mind. I'd intended to keep it a closely guarded secret all to myself, but since I couldn't get out on my own, I was making a special exception and sharing it.

Taking out a paper carton I had set aside earlier, I spoke.

“Everyone. While you were all lazing about in this bottomless pit, I went through all manner of hardships searching for a way out.”

I'd pestered the golem relentlessly to request supplies, inspected every single item that came down, and engaged in psychological warfare with the golem.

The days might have seemed peaceful, but behind the scenes, I had been working tirelessly. And finally...

I just read Lieutenant General Ebon's memories and found out.

... It made everything I'd done so far feel pointless, but hopefully my efforts still had some value.

“After personally dismantling every item sent down by the Military State, I discovered something astonishing. Namely...”

As I spoke, I scattered the contents of the paper carton over the lectern. Fine grains slid out and rolled across the unfamiliar surface.

The Regressor tilted her head.

“Dirt?”

“That's right. Dirt!”

I spread my arms and proclaimed it as though I had made a tremendous discovery.

“Every single thing the Military State dropped down here! Whether it was in a parachute, carried on someone's person, or packed into some tiny crevice! Every last one contained soil from the surface!”

That was what my painstaking inspections of each and every item had uncovered.

While the rest of you were busy playing around, mind you.

“Normally, not a speck of soil falls into this place, cursed as it is by Mother Earth. Otherwise, there's no way the ground around such a massive hole wouldn't have crumbled into it. Even if you throw a grain of sand into the bottomless pit, it will cling to the wall of its own accord and return to Mother Earth's embrace... But! That is precisely why this soil can serve as a catalyst!”

The Regressor, who had some knowledge of magic, quickly caught my meaning.

“A catalyst?”

“Yes! The bottomless pit is a place where you fall forever. But where in this world is there an infinite space? The earth is round, so if you fell forever, you should come out on the other side! Yet we don't. Why?”

I drew two long lines on the blackboard. Leaving a break in the middle to indicate their infinite length, I drew Tantalus and added a large question mark.

“Because in this bottomless pit, coordinates and space itself lose all meaning! Everyone here becomes a lost soul, doing nothing but falling endlessly!”

“... But if space itself has no meaning, then to reach something inside it...”

Having caught on, the Regressor murmured to herself. I nodded emphatically and marked Tantalus with a large star.

“Exactly. Beneath the night sky, on a pitch-black, boundless sea, the light of a lighthouse becomes a destination, a landmark, a set of coordinates. Tantalus, too, was made to serve as a landmark within the bottomless pit. How?”

What followed was something I had worked out by combining my own conjectures with the memories I'd read from Ebon. I proclaimed it to everyone.

“Because when Tantalus was built, a priest of Mother Earth bestowed a blessing upon it! Upon this entire patch of ground, no less!”

“... I'm surprised they agreed to that. For a priest of Mother Earth, the bottomless pit should be a place they must never even approach.”

Yes, I'd thought so too.

The Regressor deserved some credit for this discovery as well. No matter how I looked at it, the woman in her recollections had to be a priest of Mother Earth.

“Even if the entire ground is concrete, its substance comes from the earth. They laid the ground and erected the building using concrete made from blessed sand and gravel. Still, whatever its earthly origins, this concrete remains a man-made structure. Poised on the boundary between Mother Earth's flesh and a human building, Tantalus was able to maintain a precarious balance.”

An infinite space, and the only patch of ground within it.

They had built a prison on a contradiction that should not exist, yet plainly did.

“Only one thing is needed to reach this place. A catalyst that can pinpoint this location... soil. Simply attach it to yourself and fall, and you will arrive here naturally, just as rainwater eventually flows into the sea.”

The bracelet that had guided Finlay here, and the supply crates. All of them contained soil.

Nabi had soil attached to her too. She simply hadn't needed a parachute, since she was the King of Cats and guaranteed a safe landing.

At any rate, I understood the principle. All that remained was to apply it.

“Now, here's a question... We needed soil to reach Tantalus down here in the bottomless pit. Then, if we wanted to go up to the surface from this pit, what should we use as our catalyst?”

The undying one raised his hand first, but everything had its proper order, and even immortals had seniority. I called on Tyr, who had lifted her parasol slightly, first.

“Yes, Tyr!”

“... That would be...”

After hesitating a moment, Tyr furrowed her brow as though she found the answer deeply distasteful.

“Sunlight, I suppose.”

“Oh! Correct! Such knowledge is only to be expected of the one called the Holy See's nightmare and a being who defies the heavens!”

She got it right on the first try. What a shame.

“Oh! It wasn't a tree branch? They point toward the sky!”

'Not Sky Cherry Blossom...? Is it unsuitable as a catalyst because it's space itself...?'

I really should have heard those two wrong answers first.

I wanted to say something even now, but it was too much trouble. I'd let it slide.

“Yes. The sun! If the soil in the bottomless pit is a lighthouse, then the lighthouse in the sky is the sun. To escape this pit, we must ascend while catching its light!”

I gave Tyr a hearty round of applause for her correct answer. She waited for the clapping to stop before calmly asking,

“But surely this bottomless pit is a place where sunlight does not reach. How can we ascend while receiving sunlight here?”

I'd thought the same thing. But I had discovered Tantalus's blind spot.

Tantalus was surprisingly bright. As though imitating the sky, bright daytime lights and dim nighttime lights took turns illuminating the prison. During the day, your eyes naturally opened, and you grew accustomed to the bright light.

That was why I hadn't noticed until Ebon looked up at the sky.

The far-off heights of the bottomless pit weren't always pitch-black.

“It's not that sunlight never enters. It does sometimes, but we don't notice.”

The golem had ordered me to persuade Tyr. It had said it wasn't time to ascend yet, and that they couldn't get out that way.

But if the bottomless pit were a space no one could escape no matter what they tried, that warning was rather strange. Whether they tried to ascend or not, leaving them alone would have ensured their failure anyway. There would have been no reason to stop them.

Ebon's arrival had answered that question.

Ebon had waited on the rooftop for the right time to flee to the surface. In other words, the door opened at a set time.

That was probably why the golem had tried to stop the two of them. It feared that vampires, who needed neither food nor drink and rarely grew bored... might keep ascending until the door opened, until sunlight shone upon them.

It had told me to stop Tyr because it was worried she might brute-force her way out.

“The time when the noonday sun is directly overhead. When its endlessly extending rays must reach even the deepest depths.”

Every piece of the puzzle was in place. I declared confidently,

“That will happen in three months. At noon three months from now, in the brief moment when the sun passes over the bottomless pit. That moment, and that moment alone, will be our chance to escape.”

It was an incredible discovery, but the response was more muted than I'd expected.

After all, the Regressor had only just announced that we could get out in nine months. Reducing that wait to a third didn't cause much of a stir.

“Remarkable, Hugh. Have you unraveled even the secrets of the bottomless pit?”

Only Tyr, who was interested in my story for its own sake, was genuinely delighted.

Still, being able to leave in ninety days was encouraging. Now that we understood how the pit worked, even if we missed the next chance, we could escape whenever another came along. We no longer had to pin our hopes on a woman who might or might not turn up.

It would have been impossible alone, since I couldn't ascend against gravity, but with Tyr and the Regressor, it should be possible...

“Huh? Good point.”

Then, as though something had suddenly occurred to her, the Regressor asked,

“How did you find out? Did you get it out of the lieutenant general?”

To be precise, I'd read his thoughts.

Lieutenant General Ebon had only known what time the door opened, not the exact principles behind it. All he'd known was that he could ascend when the sunlight shone in.

Well, fair enough. A general only needed to know a code, not master the principles of cryptography.

I'd merely gathered the information they had and pieced it together to reach a conclusion.

But explaining all that was too much trouble, so I gave a casual nod.

“That's ri...”

“I doubt it! After my punches, he was practically dead! He couldn't even speak!”

The undying one answered before I could.

The Regressor's expression grew increasingly suspicious. I stared at the undying one with my mouth hanging open.

You oblivious idiot! Why do you think I asked you to cover your ears?

Seeing my expression, the undying one's eyes widened too.

'Was I not supposed to say that? Good grief, so many secrets. Very well. I'll make something up.'

Please do. I couldn't afford to look any more suspicious.

A mysterious fellow they happened to cross paths with in the bottomless pit.

That was all I wanted them to remember me as.

That was why I was trying to get out of the pit as quickly as possible.

“Then what? What did you do to someone who couldn't even speak?”

As the Regressor pressed him, the undying one thought for a moment, then thrust up his thumb and declared,

“Our teacher spent most of the time muttering something to himself! I had my ears covered, so I can't say for certain! But he probably found the answer to the bottomless pit himself and then confirmed it with the lieutenant general!”

'There, done! Now our teacher must seem even more impressive!'

... You made me even more suspicious!

Just tell her I extracted the information from the lieutenant general. That's closer to the truth!

“You figured out how to escape the bottomless pit on your own? Well, that's impressive.”

The Regressor murmured with feigned indifference, even as she focused all her senses on me.

“But all right. You certainly aren't an officer.”

“Haha. That's right. I'm a convict laborer...”

“A mere convict laborer can't kill a colonel. Or deflect Sky Cherry Blossom. Everyone knows you're no ordinary convict laborer. How long are you going to keep hiding it?”

Her movements were slow and probing. Without much expectation, but still hoping I would, the Regressor asked,

“Are you really not going to tell us who you are?”

'If you'd just give me... certainty. If I could only judge whether I can trust you, or whether I mustn't...'

For the Regressor, who had a terminal case of suspicion, my very existence seemed unbearably troubling.

The desire to trust me coexisted with an utter inability to do so. Even she couldn't make sense of her feelings.

But there was nothing I could do about it.

I'd survived, so wasn't it about time I started making preparations for the me in her next run?

Which meant I had to get through this somehow.

I heaved a deep sigh and spoke.