With the gacha cleared out and Abel on his feet (whether he ought to have been or not), there was really nothing keeping you from moving along. The door opened out to the same scene as before—the wasteland rushing past, the massive train wheels churning, and the single walkway to the next door. What awaited you in the next car? Nothing gave you the slightest hint, Neko-Neko included.
So then, only one way to find out.
The door opened the same as all the others, and you moved inside before the worrisome rumble and creak of the train could threaten to pitch you aside.
The air smelled of ink and old books with the faintest tinge of wood. Though not as expansive as the first car, the room still stretched out wide: large cloth bins, desks, smaller baskets, walls of cubbyholes. It was hard to get a clear idea of the flooring at a glance—despite all the organizers, the room was filled with so many letters no surface was safe. More seemed to blink into existence anytime you looked away.
While Neko-Neko seemed content to let the room speak for itself (or at least too busy deciding what to knock off shelves), they weren’t the only Denizen in sight. Though he’d looked up from his work when you all walked in, he seemed too taken aback by the size of your party to do anything but blink. He eventually shook it off.

“Ah, um… Hello. My name is Mahavir.”
He continued to sort the letters in his hands as he spoke.

“Please make yourselves at home, as far as you can.” He coughed into his shoulder. “It’s impossible not to step on a few letters as you go along, so I only ask that you try not to damage them. If any are addressed to you, of course you’re free to take or open those. It, er… saves me a trip?”
Something made you feel like he’s trying to joke around, but his delivery was terrible. He stifled another cough, the flame of his hair sputtering a bit.

“But don’t worry about adding to it, either. That is, if you’d like to write a letter of your own, I have the supplies necessary.”

“Oh, but I ought to tell you—if you open the letter addressed to you here, you won’t be able to send one, and vise versa. But you’ll have to do one or the other if you’d like to leave this car. I’d be happy to help with either, if you’d like me to.”

“The Train is… a complicated place. I’m afraid I understand little of it myself, but—” cough—“please let me know if I can be of assistance.”
He dipped his head and hurried a few steps over to wrangle a newly-minted pile of old letters on the floor.
Well… At least he seemed cooperative? And if you could send out some kind of request for help…
It was hard to know what to hope for anymore. But it couldn’t hurt to start looking around, at least.
—
[Car Reference Post]