My System: An Evolved Computer I Made With My Unique Ability—

Generally, the boiling temperature of water in a sauna isn't that harmful. Still, it would be an entirely different case if the temperature were to rise drastically higher than that. Satoshi and the others knew exactly that, but they still went through with the challenge since they didn't want to go back on their word.

Besides, they were keen on winning the entire thing, so there was no way they'd rush out first and risk screaming a love confession by the rooftop. There was no going back now since the challenge had already commenced.

"Are you kidding me, Satoshi?" Himuro gritted his teeth, as the steam painfully stung his skin.

"Seriously, Satoshi?!" Yun Zhe also exclaimed as he desperately covered his face, somehow partly blocking the steam that threateningly oozed out from the stones.

Wearing a grin on his face, Satoshi also felt everything they endured but he wore his poker face so it wouldn't seem like he was gravely affected by his actions. In pain, he walked towards his usual seat, comfortably seating himself as he resumed the trial he set before all of them.

The challenge had just gotten unusually harder, with their skins screaming the terrible suffering they felt. Jonathan wanted to go out, but he didn't want to be the first one to go.

Then there was Yun Zhe, who was concentrating solely on evening out his breathing. He knew that he could outlast the three of them if he focused long enough.

And there was Himuro, who couldn't even focus anymore. He just wanted to go home. This wasn't what he signed up for... nevertheless, there was no way he'd be the first to go out.

"Now, that's more like it." Himuro forced out his lungs as he rigidly sat still. The others also assumed their position farthest from the sauna stones.

All of them were heating up, steam coming out of their body as their skin turned into a pinkish hue. One wrong move or one large breath would be enough to send pain signals up their brain.

Continuously, the sauna stones released steam, filling the entire room with it. The temperature continued to rise up but at this point, the four of them had gotten somewhat used to it. They didn't dare move, though, since they'd immediately feel the stinging pain on their skin.

"Y'all can go out. I'll be staying here a couple more minutes." Himuro called out. To be fair, he already wanted to go out, he was just pushing past his limits so he won't be the first one to go.

"You're looking kinda uncomfortable there Himuro." Yun Zhe commented. "If you want, you can head out first."

"Yeah, and then head straight to the rooftop and confess your feelings to Hermione Ranger-san." Jonathan continued. "Then again, Hermione-san is beautiful... I might go out first and confess instead." He joked.

"Then go ahead, no one's stopping you from confessing. In fact, we'll even help you, right?" Satoshi continued, teasing Jonathan since he seemed to be seriously considering the option.

"You know what. I'll take the fall for all of you guys. I'll be going on ahead..." Heaving a sigh, Jonathan stood up as he headed towards the door. His expression displayed his intention of going outside, so everyone concluded that he really was about to go outside.

Just when he grabbed the door handle, a smile swept across his face. He then turned around, chuckling. "Just kidding! I won't be the first one to go. You guys can go on ahead before me."

"You know, you can still confess to her even if you win, right?" Satoshi pointed out, twirling his index finger in the air. "No one's going to stop you."

"Ah, right! I'll go with that option then heh~" Jonathan nodded along, heading back to his seat and continuing the challenge.

It was clear that none of them wanted to go outside no matter what, which meant that they'd be staying in the sauna until they lose consciousness. The four of them didn't budge as the minutes passed by.

When the five-minute mark hit, Satoshi decided to stand up to get some water by the corner. Without further ado, he poured another batch of water on the sauna stones just to keep the temperature fresh.

Everyone was gasping for air at the ten-minute mark, but then again

A blast of steam hit him straight in the face, but he didn't flinch. Instead, he went back to his seat as quietly as he could. Even though he didn't utter a single word, he directly challenge everyone to put more water and produce more steam.

There was no backing down now. The next one to stand up was Himuro, pouring more water into the stones in an attempt to send someone out.

The temperature rose to two hundred and ten, and they were burning up. Their breathing became more ragged and their lungs started to constrict. The amount of oxygen in the room had been compromised and they were barely hanging in there.I think you should take a look at

To be fair, this sauna was constructed with the thought of training someone's temperature immunity as a superhero. That's why it could easily rise up to an insane temperature. Unbeknownst to the four of them, it could even be used to develop immunity to the cold since it could go the other way, lowering the temperature to a crazy number.

At this point, no one spoke anymore. They were so close to losing consciousness due to how hot the place was. It's as if death was knocking right on their doorstep.

Their throats dried up, and they wanted to drink some water. However, all of the unanimously assumed that drinking water was synonymous with accepting their inferiority so none of them drank.

Jonathan went up next, walking towards the sauna stones and putting more water on it. The entire room was filled with steam, so much so that they could barely see each other. Then again, they could still sense themselves so they'd know in an instant if someone were to use their superpower or not.

When the twenty-minute mark hit, they heard a sudden plop on the ground, causing them to whirl around, surprised. The first thing they noticed was that Jonathan was the first one to hit the bucket, falling into unconsciousness while he was sitting down. He lurched forward, causing the plop which everyone heard.

"HAH! We have ourselves a losee-ughH~" Himuro trailed off as his eyes rolled to the back of his head. The moment he stood up, his blood cycle had gone haywire and he blacked out. He passed out in an instant, falling on top of Jonathan who was already sprawled on the ground like a rotting cadaver.

"HAHA! And the second one bites the dust. I guess between me and you now Hajime-ughhh~" Yun Zhe felt all the strength in his body leaving him as he fell sideways. His control over his body became nonexistent as he drifted into slumber. As it turned out, he'd reached his limit and he also fell into unconsciousness just like Jonathan and Himuro. 

"Oi~! What are you guys doing?!" Satoshi screamed, shaking them awake. Even he was on the verge of losing consciousness. However, if he fainted right then and there, all four of them might die together.

Well, not really since their bodies would automatically switch to using their superpower.

Before any of them could wake up, Satoshi grabbed all of them, slinging Jonathan and Yun Zhe on his shoulder while he dragged Himuro to the floor. His head started spinning but he pushed himself to get all of them out of there before the worst-case scenario transpired.

"Spend time in the sauna they said, it would be fun they said," Satoshi said to himself as he opened the door to the sauna, bringing everyone out as he fell on top of all of them.

...

Meanwhile,

Now that everything was in place, and they'd already cleaned their place up, Nanako and Mitsuka decided to head to the sauna so they could either get the boys or join them in their fun.

"How could they hold a sauna contest in just half an hour? They should last longer than that." Nanako questioned as she and Mitsuka made their way to the sauna.

"Nah, they probably have something else in mind. You know, the three of them seemed to regard each other as rivals." Mitsuka responded.

"Yeah, there's probably something more to it. We should go see them before they get into some sort of trouble."

Quickening their pace, the three of them hurried to the common area, then out to the open area in the middle of the dorm. From afar, they saw the sauna and they sprinted towards it.

The moment they arrived in front of the sauna, they couldn't even see through the glass door due to how thick the steam was inside.

BAM!

To their surprise, the door suddenly slammed open, and out came Satoshi, holding the other three since they were all unconscious.

"Ah, good thing you're here. As you can see, I won the challenge." Satoshi pointed out before he collapsed in front of Nanako and Mitsuka.

"What on actual—" Mitsuka couldn't help but exclaim.