"Even though a planet is spherical, gravity makes it feel normal when you live on it—no matter where you are, the sky is always overhead."
Jiang Bai drew a cross-section in the sand. "Inside a planet is endless rock, blistering magma, and all kinds of solid matter. There might be cracks or chasms, sure—but there can't be an underground space larger than the surface."
"And planets like that make up vast galaxies—then the universe."
Albedo listened intently. This was knowledge he didn't have. Even if it didn't apply to Teyvat, it was still useful as a reference.
"In my experience, if someone stays underground too long without sunlight, it can seriously mess with their head." Jiang Bai paused. "Though… if they've never seen the sun in the first place, maybe it's different."
Like him. He'd once spent a long time in a pitch-dark, danger-filled place. It had taken a real toll—and it was one of the reasons he'd been so insecure back then.
But after more than a year of living like a normal person, that problem had eased.
"I used to think Teyvat was a planet too," Jiang Bai said with a sigh. "Sure, it has gods and elemental power, but I figured it was still just a planet in the universe."
Teyvat kept shattering his assumptions.
The false sky, constellations, the Abyss, Celestia… none of it could be judged by common sense.
"Your memories have returned?" Albedo looked up at him.
Clearly, Jiang Bai had recovered quite a lot—otherwise he wouldn't know so much.
"I've gotten a lot back." Jiang Bai nodded.
His memories of home were distant beyond measure, but even so, when he spoke of them, it came out almost instinctively.
Albedo didn't rush to press him. He simply followed the thread.
He drew a single horizontal line in the sand. "What if Teyvat is more like this?"
"This line is the ground. Above it is the sky. Below it is the underground."
And the false sky… covered everything overhead, beyond Celestia.
Then he drew countless crisscrossing lines beneath the horizontal stroke—interwoven like the roots of an inverted tree.
"These are the pale ancient trees that run through the underground. These connected branches record all of Teyvat's information. This is what we call the ley lines."
Jiang Bai watched him draw, listening.
"If it's a tree, then where's the canopy? The leaves?" Jiang Bai frowned. "If it's towering, we should be able to see it."
A normal tree had roots—and it had leaves.
If the roots spread across all of Teyvat, then where were the leaves?
Albedo answered with a question. "Have you heard of Irminsul?"
"No." Jiang Bai shook his head.
"Irminsul—like the ley lines—stores all kinds of information about Teyvat." Albedo rested his chin on his hand. "I've been wondering… could Irminsul be the aboveground part of that pale ancient tree?"
Jiang Bai scratched his head. It was his first time hearing the term Irminsul.
But was it really the surface half of that tree? If the goal was recording the world's information, wouldn't one system be enough? Why have both ley lines and Irminsul?
And Dragonspine had that withered pale ancient tree too—wouldn't that count as an aboveground portion?
Still, these were hypotheses. With too little information, you made bold guesses and tested them carefully.
"Then where is Irminsul?" Jiang Bai tilted his head.
"I've never seen it either. Maybe it exists in a place we can't normally reach." Albedo's voice stayed thoughtful. "Perhaps when we meet Sumeru's Dendro Archon, we'll be able to see it."
Albedo hadn't seen Irminsul; he only knew it existed from documents and scattered records.
Its concept was close to that of the ley lines—both were said to store all information about Teyvat—which was why he suspected Irminsul might be the aboveground portion of that immense tree.
Setting that aside, Albedo continued drawing. He sketched a circle that enclosed both sky and earth.
The circle looked like a bubble, wrapping Teyvat inside.
"Teyvat has a boundary. That boundary protects it. Aunt Alice is currently working on repairing it."
That much he could say with confidence—Alice herself was proof.
As for whether the boundary truly looked like this… he didn't know.
"You mean Klee's mom?" Jiang Bai asked.
Albedo nodded. "Mm."
Alice hadn't left her young daughter with the Knights of Favonius for no reason. She had something more important to do—something that didn't allow her to stay by Klee's side.
"Then what's outside the boundary?" Jiang Bai's gaze drifted to the sand beyond the circle. "What's out there?"
"I don't know. I've never been to the boundary. Maybe Aunt Alice has."
Albedo brushed the sand smooth, erasing the drawings. "For now, these are only my guesses—working hypotheses for my research. What the truth actually is… we still don't know."
Even so, Jiang Bai had a feeling Albedo's "guesses" were dangerously close.
Either way, he couldn't accept the idea that Teyvat was a sphere anymore.
Albedo brought the topic back to five hundred years ago.
"Five hundred years ago, the underground nation of Khaenri'ah was destroyed. Countless Ruin Guards poured out from beneath the earth. And not long after that, a tribe that worships the Eclipse appeared in Dadaupa Gorge."
He didn't know Khaenri'ah's exact location. It likely had multiple entrances, reaching into much of Teyvat.
When Khaenri'ah fell, a tide of pitch-black calamity surged out, affecting all seven nations.
Albedo hadn't been born yet. He only knew these events through books and records.
In any case, for everyone, what happened five hundred years ago wasn't a pleasant memory.
"Did the people of Khaenri'ah worship the Eclipse?" Jiang Bai asked, cutting straight to the point.
If Khaenri'ah also worshiped the Eclipse, then he had to consider the possibility that these hilichurls… were once Khaenri'ahns.
Albedo stayed silent for a long time.
That silence was as good as an answer.
A thunderclap seemed to go off in Jiang Bai's head.
Goosebumps rippled across his arms. A cold chill crawled up his spine.
Humans turning into monsters—creepy. Way too creepy.
Ever since he'd realized Teyvat was messed up, more and more messed-up things had started parading right in front of him.
No wonder people needed the gods' protection. Without it, he didn't feel safe at all.
He needed to cling to Zhongli's leg for dear life.
And Venti too—he should drop by and bring him wine every now and then. Useless as he was most of the time, he was still a god. At least he might come through when it truly mattered.
"The origin of hilichurls is still a mystery," Albedo said at last. "Let's drop it for now."