Perhaps it was deep, and normally, Atsuko didn’t have the time of day for these sorts of conversations. But this train had already set her on a track she wasn’t used to, made her think in ways she wasn’t used to. Or perhaps she was already down this path, and the train had just been the catalyst for those sparks of thoughts to burn into a full flame in her mind.
Atsuko watched Haruka with that same expression, showing no indication that the words got through to her at all. For the most part.
Haruka Yukimura "There’s no point setting yourself alight to keep others warm, is there? Haha…”
The innkeeper gripped the strap of her bag, head turning away from Haruka. Her gaze settled on… well, nothing in particular. She just wanted to not be looking at Haruka, she wanted to think without having her gaze returned.

“…I see.”
For a moment, that was all she said. She wasn’t sure what else there was for her to say. The scarf had been returned, Atsuko came to understand why Haruka did what she did, that should have been all. The problem is that Atsuko didn’t truly understand, because she could never relate. And that just meant that continuing to think about such things would only exhaust her.
And yet, feelings and thoughts she hadn’t felt for years were bubbling up again to the surface. Coming on this train had been a mistake after all, because ultimately, there was nothing here for her to learn that she didn’t already know.
She finally turned her head back toward Haruka and spoke.

“Perhaps we’re two extremes, then. I may have the… smarter approach, but I already know what other people think of me outside of this train. Surely, you… are someone who is much more liked. So it just becomes… a matter of priorities. Our priorities… are likely not the same, because we’re so different. So if helping others, even at your own expense, is what makes you the happiest, then you should do it.”
In doing so, Atsuko answered any returning question Haruka might have had of what Atsuko’s own thoughts on self-sacrifice are, if it hadn’t been clear already. Atsuko couldn’t understand, and despite being near-strangers, that was one thing Haruka could understand about the innkeeper.