Best Friend X Swap

“Wow, what is that?”
Entering the address sent by the production team and driving for about ten minutes, they arrived at a well-known indoor climbing center in the area. After following the instructions to rent climbing shoes and changing into them, they stepped inside—only to be greeted by a huge space filled with bright, colorful holds scattered across every wall.
Seo-eul, who had only ever known climbing as something that existed “somewhere out there,” had never imagined doing it himself. His eyes widened at the towering blocks stretching all the way to the ceiling. He had no idea how people were supposed to use any of that. While he was busy staring nervously, Ye Ju-yeol, who walked in behind him, puffed out his chest and declared:
“Uhaha! Looks fun, right? This place is the biggest around here and has tons of problems, so I strongly recommended it to the PD! Actually, I live too far to come often, but whenever I want to spend an entire day climbing, I always visit! And coincidentally! Turns out it’s not far from our house!”
Considering he barely ever came yet still bought a membership, that said it all.
Excited like someone who’d been given an unexpected present, Ju-yeol stretched his arms high and asked the two:
“You both said this is your first time climbing, right? Not even videos?”
“Mm… I think I just passed by something once. I’ve never been to a place like this.”
“Aha! Then I’ll teach you everything today. This place is a route paradise. Once you learn the basics and start solving them, it’s really fun!”
Seo-eul had no idea why a route was “delicious” or what he was supposed to be “solving,” but because Sa-heon said nothing, he nodded for him and answered with a teasing smile.
“Okay, I’ll count on you. Today you’re our senior.”
“……!”
Senior.
Did he hallucinate?
The word, something he used dozens of times a day, sounded suddenly majestic when spoken by Seo-eul.
The fact that he could finally teach something to the person he’d always admired—it sent his mood soaring to astronomical heights. His grin already stretched toward his ears, but now it practically wrapped around his head.
I’m a senior. I’m senior to my senior…!
He felt like he could instantly kick the hardest black hold and plant his foot on the ceiling.
“Uh-hat…!”
Unable to contain himself, Ju-yeol turned around quickly. Overwhelmed, he lifted both arms high in a silent personal celebration. Watching his friend act like that, only Yoon Hyuk—who had witnessed every second of this insanity—frowned deeply.
This lunatic.
He was ranting about never living together again this morning, and now he’d turned into some giant cartoon character.
Specifically, a giant Crayon Shin-chan who ate 467,394 bowls of rice.
“Hyuk, what about you?”
Still watching his suspiciously delighted best friend, Seo-eul casually turned to Yoon Hyuk and asked. Even though the reaction had been absurd, somehow… after yesterday’s series of odd behaviors, they all seemed to have adapted.
Or given up?
Whatever it was, it was embarrassing.

“I did come once before… but it was when I was managing a wrist injury, so I only watched from below.”
At the mention of an injury, Seo-eul blinked hard.
“Injury?”
“Ah, I slipped on a lift… It was just a small twist, so I’m fine now. Other than filming him, I’ve never tried it myself.”
That day, he had come to “just watch” because of Ju-yeol’s endless recommendations—and witnessed Ju-yeol flying across the wall like Tarzan.
Hyuk had given up climbing on the spot.
Not because of Ju-yeol refusing to come down once he grabbed a hold, but because the sport actually looked pretty dangerous. As someone whose body was his job, Hyuk filtered out anything with higher injury risk.
He knew very well that if he got hurt, there were people who’d be more heartbroken than he was.
Because he committed fully to his main job, he avoided unnecessary risks in his off time. During fanmeeting or concert seasons, he often disappeared entirely, buried in practice rooms and studios. Practicing even once more to raise performance quality made him feel at ease. He was that strict with himself, that sincere with feedback.
And really—wasn’t it obvious?
Fans spent tens and hundreds just to see him.
He could not repay that 100%, but he wanted to give as much as he could. Facing disappointed fans would be worse. He’d rather grit his teeth and deliver. He was the type of person who would rather die than make liking him embarrassing. His nature simply did not allow compromise.
So he had rejected all of Ju-yeol’s whining about going “just one more time”…
And yet here he was.
Truly—life was unpredictable.
Now fully composed again, Ju-yeol spun around and called out firmly:
“This might look easy, but if you climb without warming up properly, you can get injured. So we’ll start with stretching and warming up.”
These were people whose bodies were their livelihoods. Worried they might come happily only to get hurt, even eternally-grinning Ju-yeol put on a rare serious face.
While they were warming up together, he suddenly noticed something and his eyes sparkled.
“Oh! Do you know what that is?”
Loosening his wrist, Seo-eul followed the direction he pointed. There was a strange-looking board with slanted panels, rows of round holds, and long stick-like bars reaching toward the ceiling.
“This is a campus board. It’s a supplementary exercise that builds finger strength.”
Saying so, he reached up and grabbed a bar with both hands, climbing up one rung at a time. With perfect form, he hit the top and dropped down lightly. Intrigued, Seo-eul walked up and grabbed the bar too.
Okay, he grabbed it but—
“…Huh?”
He barely managed two rungs before he dangled like a pendulum and slipped off.
Even 90 degrees would be hard—but this was a slanted board, so he slid instantly.
“What the heck. How did you do that?”
“You have to press with {N•o•v•e•l•i•g•h•t} your wrists. If you fully straighten your arms, you’ll get ripped off—keep them bent!”
While he was receiving the crash course, Yoon Hyuk and Sa-heon approached. Provoked by Ju-yeol’s region-wide challenge of “Can you climb it?”, Hyuk tried too—but dropped off just as fast.
What the—why does it slip like that?
“You try.”
Watching them, Seo-eul poked Sa-heon in the ribs.
Sa-heon, who looked equally uninterested whether it was grabbing bars or climbing trees, loosened his hands once, grabbed the bar, and immediately climbed—block by block—straight to the top and back down in seconds.
“Holy sh—your body is what…”
Staring in shock, Ju-yeol rushed over. Sa-heon was busy fixing the sleeve that had rolled up while climbing the board. His forearms, veins standing out, and well-shaped arm muscles were fully visible.
“Uh, do you do weights? Can I touch your triceps?”
“Pay me.”
“How much?”
“Not sure. Seo-eul, how much should I charge?”
He did not even glance at the mesmerized Ju-yeol and instead asked Seo-eul. When Seo-eul looked back with an expression that said, What nonsense are you spouting now, a faint mischief flashed across his usually stoic face.
“How much have you looked into paying?”
“Cards don’t work, right…?”
“No. Transaction fees.”
The absurdity escalating by the second left Seo-eul dumbfounded. He reached to pull Sa-heon away by the arm—
“Hello. I’m Kim Ji-hu, and I’ll be your instructor today.”
A voice came from right beside them. All four turned at once. Appearing carefully as if waiting for the right opening, he was the professional instructor the production team had hired in case of safety issues. Except for Ju-yeol, the other three were complete beginners, so a short lesson seemed necessary.
After a brief exchange of greetings, he got right to the point.
“Since everyone except Ju-yeol is new, we’ll be using the bouldering zone today—no ropes. I’ll start with some terminology. These rocks on the wall are called holds. There are tons of colors, right? Obviously you can’t step on everything. You must only use the holds in the color of the problem you’re attempting. You start at the ‘S’ hold here, and if you grab the ‘T’ hold up top with both hands and hold for three seconds, that’s a clear. Simple, right?”
The rules were simpler than expected. Seo-eul nodded with a focused expression. Then, unexpectedly, Sa-heon—who’d been quiet until now—asked:
“Then will we be continuing without ropes the whole time?”
The slight hardness in his voice made the instructor respond quickly.
“Yes. Since you’re all beginners, bouldering is safer. Rope routes aren’t possible today because of our schedule. But once you practice today, you can always come back and try rope climbing next time…”
In other words, this was the only option.
After explaining a few more safety guidelines, the instructor clapped once.
“Practice is better than explanation, so let’s grab the wall. Seo-eul, would you like to go first?”
“Ah—yes.”
He had not expected to be the first. As he hesitated and started walking forward, someone grabbed his wrist. He turned—and saw Sa-heon wearing a strangely unreadable expression.
Why? he mouthed silently.
“…Are you okay?” asked Sa-heon.