"Well...if you have to know: to me, you seem important. Everyone around here has been through so much, I'm even getting more involved in ways like Marisa has! Or Reimu! We all have to start living through as much as we can eventually..."
A terribly distant conversation with a stray Tengu by the Pond many moons ago echoed from the back of Cirno's memories, part of her hoping that what she'd have to say could at least carry a little of the same weight as the advice shared back then.
"My point is that I've seen enough to know when someone is gonna start making things happen around here, and I want to be there when those things start happening! Important people thrive within Gensokyo even under the craziest of conditions and here you still are."
"Hmph. Seems a little selfish, don't you think?"
"Big deal. Like you're better off dead to anyone important around here anyways. At least when you're alive you can worry more about your own safety yourself..."
"Ah, speaking of: you're still going to be okay on guard duty for the rest of the night, right?"
"As solid as a frozen rock~! Nobody else will be seeing Miss Usami tonight!"
Even if Cirno was partially full of hot air, that was good enough for Renko to lull herself to sleep once again. The curtain was fully drawn shut this time, the girl hearing little more than the continuous crunching of Cirno's scurrying just outside the Igloo doing who knows what. So long as chances like these kept popping up, Renko knew she really could keep going on her own under so much pressure. One peaceful rest at a time...

Of course, there was no easy way to tell when exactly she fell asleep again, but the next time Renko woke up it was clear to see that it was nearly mid-day. The sun had risen high above the surrounding hills & mountains and the gentle Autumn light had been beaming through the Igloo's porthole directly into the Physicist's face. It wasn't uncomfortable but it was a sign that it was time to get moving. Her body did feel a lot better, can't afford to stick around until something else comes along to spoil that.
In a few minutes, Renko had made just about the only adjustment to her outfit she could - changing into the single spare shirt within her handbag and donning her only headband - and gotten everything ready to go find Cirno. The Physicist wasn't thrilled that she had to resort to wearing what was essentially a dress shirt fit for a night on the town but that long-sleeve had just gotten too grimy. Like her only other company at the moment would even care anyways, the Ice Fairy herself being conspicuously absent from her own Igloo. She couldn't have gotten far, unless she somehow really did stay up the whole night...

Evidently enough, it seems she did stay up until passing out involuntarily at some point. Renko hadn't even taken 5 steps outside before stumbling across Cirno's unconscious body face-down in the snow, completely asleep after what seemingly culminated in an all-out Total War between her desecrated snowman army strewn across every frost-laden inch of the violent powdery wreckage that was now the hilltop. The Ice Fairy was splayed out next to several large ice-spears she seemed to have been carrying before losing all stamina.
How long had she just been lying here like this for..?
"Cirno, hey, Cirno! Wake up! I need to talk to you about something." Renko hunches herself down near Cirno and gives a few good firm shakes to her shoulder, hoping she at least had the bare minimum of hours necessary to function behind her.
"Hhnzzmnnhggh...gbehgehnnzzmnhh...prrimninnzzhnmmn..."
"/Cirno!/"
"Fivemoremiinnizznnhh..."
She limply shooed Renko away with one hand while still face-first in the snow to no avail. Renko was nearly ready to lift her out of the snow herself before an unexpected arrival seemingly appeared out of thin air with little fanfare.

"Oh my, and what on Earth happened here last night?"

A green-haired fairy with fine, feathery wings that Renko had never seen before fluttered down from the mist surrounding the Lake. She had a single ponytail off to the side kept with a yellow ribbon and didn't even notice the college girl until they were mere meters apart. Daiyousei let out a small gasp upon locking eyes with Renko looming over an incredibly groggy Cirno, unsure of whether or not she should flee from this strange human just to be safe.
Up close, she seemed to stand just a little taller than Cirno but could still only barely graze Renko's neck at best. The Physicist figured she's already run into enough people at this point, what's the harm in getting used to breaking the ice herself?
"Uh, hi there? Can I help you..?"
"O-Oh, uh, w-well...I really just came to get Cirno. Is she okay down there..?"
"Hhhaaaiidonevnnmm...yugihgh...howziwhoziwhatsitto...the—Gah! Hey..!"
Renko decided she had enough of trying to translate Cirno's gibberish and simply packed together a snowball to be thrown into the Ice Fairy's face, everyone finally on nearly the same page.