Edo is a vast town, but if you ask what stands as its symbol, the answer comes back the same every time: the Sky Tree, the Tenkūju.
It is a colossal tree growing smack in the middle of Edo, said to stand a full thousand meters tall, though truth be told it likely falls well short of that.
Symbol of Edo it may be, but the inside of the Sky Tree has become nothing less than a den of demons.
Rumor has it that, long ago, back in the age of the Insect-Forest Civilization, the place served as something like a modest palace, and all manner of treasures are said to lie hidden within still. But the higher one climbs the Sky Tree, the more abnormally powerful the enemies become, and it is said that no one has ever set foot upon its very top.
Being a nest of such dangerous demons, and sitting right in the heart of Edo besides, it naturally has gatekeepers posted at its foot.
The base of the Sky Tree is ringed by a great earthen wall, and just beyond that stands a checkpoint, so that demons cannot simply come and go as they please.
Yasutaka made his way to the checkpoint's reception desk.
"I'm here on a request from the Northern Magistrate's Office. I'll be entering Checkpoint Tatsu Number Five."
"What's the job?"
"Uh, well......"
Peppered with questions by the gatekeeper, Yasutaka explained himself in detail and was granted leave to enter.
For the occasion he wore his full suit of armor along with all his adventuring gear, and he handed over the iron token, the mark of a Kabukimono, that had been hanging around his neck.
The gatekeeper took it and stamped his entry into the laborer's registry he kept close at hand.
"There you go. Try not to die out there."
Gruff as ever, the gatekeeper said this and swung the gate open for him.
Naturally enough, the ground near the base was kept clean, since demons were cleared out from around it every single morning.
Yasutaka and his companions headed for the vine coiled at the base of the Sky Tree, and from there began their climb.
A great vine wound its way around the Sky Tree, tracing a gentle slope as it went, and thanks to it a person could walk right up this towering, impossibly tall trunk on foot.
Seeing it, Granny Moon knit her brow.
"We're climbing that?"
"Can't be helped, can it?"
Wearing a look of pure distaste, Granny Moon nonetheless made to climb along with the rest, when...
"Hold up there, you lot."
"What is it?"
Called back by the gatekeeper, Yasutaka turned around.
"There's a warning out on Tatsu Number Five. Lately a lot of Kabukimono haven't been coming back. Watch yourselves."
"A lot of Kabukimono haven't been coming back?"
"That's right."
The gatekeeper held out the laborer's registry to show him, so Yasutaka climbed back down off the vine to take a look for himself.
Mōha followed suit and began looking it over as well.
"Look here. Tatsu Number Five is the only one where hardly anybody's come back."
"......"
Yasutaka scowled as he studied the registry.
Just as with his own entry, the stamps marking arrival were all present, but the stamps marking return were not.
That meant those people had been killed by demons and never made it out again.
Kabukimono were, by and large, drifters with no fixed home to begin with, so if one of them died, it was considered his own affair, and in cases like this the matter was simply left as it stood.
Still, records like these were kept all the same, if only so that someone might, every now and then, go and recover the bones and see them properly laid to rest.
They served another purpose too: wherever few travelers came back, it was plain that danger there was on the rise.
The gatekeeper's face turned grave.
"Something nasty might have turned up in there. Be careful."
"...... Thanks."
With just that, Yasutaka started climbing again.
"That's worrying..."
"Yeah. Let's just wrap this up fast and get home."
Trading those words with Mōha, they climbed on upward.
Some tens of minutes later...
"Oh, this is truly hard on these old bones......"
Granny Moon climbed on doggedly, sweat streaming down her face.
A slope like this was, understandably, murder on someone of her years.
Steep as it was, Mani-hime turned to Yasutaka and asked him, cool as ever.
"Where are we going?"
"Not much farther. I should start getting ready pretty soon."
With that, Yasutaka set down his pack frame and pulled out a few tools.
Granny Moon asked, puzzled.
"Why didn't you have those out from the start, then?"
"Around here, demons hardly ever show up on the outside. The shogunate keeps a watch on this place too."
So saying, Mōha pointed up at the Bird-folk patrolling the sky above.
Always armed with bows as they wheeled through the skies over Edo, they never failed to circle the Sky Tree without fail.
Just then, they seemed to spot something, for they gathered together, loosing arrows and breaking into song all at once.
"La la la~♪ Ru ru~ ru ru~♪"
They were too far off, high up in the sky, for anyone below to make out just what they were singing, but sing they did.
And the instant they sang, flames and ice sprang into being and rained down upon what looked like a knot of demons.
Looking closer, it seemed some demon had been trying to break through to the outside, and the Bird-folk were cutting it down with both arrows and Sacred Hymn.
The Sacred Hymn, put simply, was song made into magic.
An ordinary priest could draw on the power of their own patron god, and no other's.
Mani-hime was a fine example: she could perform the miracles of the Insect King, but she had no access whatsoever to any other god's power.
The Sacred Hymn, however, was a prayer offered up to every god at once, which made it an all-purpose prayer art capable of channeling the power of any god at all, and the Bird-folk, being something like messengers of the gods themselves, made frequent use of it.
"That's the Bird-folk cutting down any demon that tries to break through into the town of Edo. That's exactly why demons hardly ever turn up outside the Sky Tree."
"I see, I see."
Granny Moon nodded, satisfied with Mōha's explanation.
Watching the preparations get underway, Mani-hime asked.
"By the way, what are we doing today?"