Elementary school students start their day early.

Well, according to school rules:

“Students must arrive by 8:15 AM.”

In other words… for the kids, everything before 8:15 is free time.

At first, Ryouhei and Kouhei would leave home at 8:00 AM because they couldn’t wake up early. But once they made friends and started playing before class, they began arriving five minutes earlier each day. By the time they were reaching school at 6:55 AM, the school sent out a notice:

“Please arrive between 7:30 and 8:15 AM.”

…The teachers must’ve had a hard time.

And so, every morning, Ryouhei and Kouhei leave for school by 7:15 AM.

For the first time in a while, Mika’s husband took a weekday off. With the backpack he packed yesterday, he was fully prepared.

Mika handed him insecticide and looked for something that could serve as a weapon, but nothing suitable turned up. In the end, she gave him a collapsible fishing net—compact when folded, but extending over two meters when opened. The handle was sturdy, and the net itself was strong.

…Though whether it would work on monsters remained to be seen.

Mika’s weapons, of course, were insecticide and a shovel.

Shouldering their backpacks, they headed to the door near the school. Even with the shovel sticking out, their odd appearance wasn’t too concerning—this gravel path led to a community garden, where people occasionally walked by carrying hoes and sickles.

Naturally, they didn’t forget to drape towels around their necks as camouflage.

At the fence, Mika checked that no one was around before quickly inserting and turning the key. Behind her, her husband gasped.

“W-Wait, Mika, you can’t just open someone else’s parking lot! We’ll get in troub—huh?!”

His words cut off abruptly.

Beyond the fence door wasn’t a parking lot—but a dimly lit cave.

Grabbing her stunned husband, Mika pulled him inside and slammed the door shut.

Of course, the door was no longer part of the fence—it was now an ordinary wooden door set into the cave’s rocky wall.

“M-M-Mika?! Wh-What is this place?! Why did we end up here?!”

“That’s just how the key works. Anyway, I wanted to check out this cave. Let’s go.”

Hoisting the shovel over her shoulder, Mika marched forward without hesitation. Her husband hurriedly assembled the fishing net and chased after her.

“Hey, Mika… haven’t you gotten a lot tougher lately?”

“…Have I?”

Turning slowly, Mika flashed him a bright smile. He fell silent.

The cave’s exit led to a narrow ledge along the cliff, with paths branching left and right.

Beyond it was a deep plunge pool, where the waterfall had frozen solid—now just a curtain of icicles dripping water into the basin below.

The pool flowed leftward into a river, so they could cross to the other side by taking the right path.

“Be careful, dear.”

“I’ll be fine, but…”

The path, about 50 centimeters wide, was uneven but easy to walk on. Given the presence of the door, it was likely man-made. They crossed safely to the other side of the plunge pool.

Glancing back, Mika saw her husband navigating the path surprisingly well. Behind him, the frozen waterfall towered brilliantly into the sky.