Summoned with an SSS-Rank Portal Skill

William pulled out the phone and checked the messages—and what he read left him a bit concerned.

The people who had created the dungeon were chatting in their group, talking about something that had happened recently.

"I think someone took the mermaid we placed in that cave, and they also took all the mana stones from there."

"Seriously? Can we track down who did it?"

"We can't… For some reason, there was another portal inside that cave. And since whoever did this didn't use one of our portals, we can't trace them."

"Another portal? Could there be a traitor among us?"

The mood among the dungeon's creators was clearly tense. William, at least, was glad he could read the messages without them noticing—thankfully, that group didn't show read receipts or indicate who had seen what.

He had already suspected there might be a traitor. It was the only logical explanation—creating a secret portal between dungeon levels without anyone noticing required an absurd level of power.

But who was the traitor? That was the hard part. William knew absolutely nothing about the other creators of the dungeon. All of them used fake names and profile pictures—codenames to hide their real identities. They could be anyone.

They talked about a few more things in the group… and one message in particular made William feel a surge of unease.

"Did you see they're trying to invade the demon island?"

"What? Seriously? How did they find the portal?"

"No idea, but it looks like the attacks have already started. This is gonna be interesting to watch."

William tensed up, anxiety bubbling in his chest. He needed to get out of the dungeon as soon as possible and return to the demon island to understand exactly what was happening.

He didn't want to waste time and end up returning only to find everything destroyed.

Those messages lit a fire under him. He clenched the phone tightly, jaw tight, eyes focused. He couldn't afford to slow down now—he had to find the way out of this dungeon, fast.

He ignored the messages and focused on finding something useful inside that place. Everything looked just... normal.

There was nothing special that caught his attention. It looked like a regular castle—completely deserted, and that was it.

As William walked down one of the hallways, Asura spoke to him mentally.

"Stop. I think there's something strange here."

William trusted his companion, so he stopped and waited, expecting Asura to explain what he meant.

"I can sense auras nearby. I think there are invisible creatures around. Be careful."

That changed everything. Had these creatures been watching him all along without him noticing? Maybe this castle wasn't as easy as it seemed.

Standing still, William focused his eyes on his surroundings, trying to spot anything unusual that could indicate another presence nearby.

At first, he saw nothing. If it were that easy, he would've noticed before. But after a few moments of staring at the same spots, he began to notice translucent silhouettes.

It was incredibly subtle at first, but once he saw them, there was no unseeing it. William counted several shapes moving through the hallway.

"There you are," he thought.

He had no idea what kind of creatures they were, so charging in recklessly wasn't the smartest move. It was better to go slow and test the waters.

He waited patiently until one of the silhouettes strayed a bit from the rest. The perfect chance to strike without drawing too much attention.

He decided not to use his sword. William sprinted toward the figure, hands empty, jumped, and tackled it to the ground.

The silhouette crashed to the floor, and its invisibility faded. William looked down—and saw a human. His eyes were blank, empty, as if something had taken over his mind.

"Hey," William said. "Who are you?"

The man didn't respond.

That's when William felt a sharp pain in his gut—and heard the sickening sound of blood dripping from his body.

The man had a knife in his hand—and had used it to stab William.

The pain was sharp, but still manageable for someone like him. William quickly disarmed the man, sending the knife flying across the floor. He kept trying to get the man to say something, anything, but nothing worked.

It was like the man wasn't even truly awake. His actions felt more like instinct or someone else's command. After a while, William gave up and decided to choke the man until he passed out.

The guy looked like a regular person, so William didn't feel the need to kill him. If it had been a bandit or some other scumbag, he wouldn't have hesitated—but this one seemed off. He clearly wasn't in his right mind.

"I bet the rest of them are the same," William thought.

He didn't want to waste time knocking each of them out one by one. Thankfully, his powerful body made that unnecessary.

He leapt over the group, kicked off the wall, and used his strength to keep moving forward, like he was scaling the corridor itself. His movements were fast, fluid, and graceful—each motion refined and efficient.

He slipped past the invisible people with ease, reaching the other side of the hallway where no one was waiting.

From there, he continued on, hoping to find something—anything—that might explain what had happened to those people.

*

After walking for a while, he eventually ran into Rena and the adventurer again. All the castle's corridors and rooms were connected, so it wasn't too surprising that they'd crossed paths again.

A welcome surprise, though.

"Find anything useful?" William asked.

Rena answered. They'd also found invisible people—strange and lifeless, just like the ones he had seen.

"Same here," William said. "One of them stabbed me, actually."

He showed them the wound. His clothes were torn and stained with dry blood, but the injury had long since healed.

"That's really weird…" Rena muttered. "What do you think happened to them?"

"I don't know," William replied, turning his head toward a massive door up ahead, "but I think we're in the right place."

The door was decorated with glowing symbols, flanked by two towering statues. The whole setup gave off an intimidating vibe. Anyone who had ever played a game before would immediately recognize it: boss room.

William had no doubt.

"I'm guessing that's where we'll find the portal—and whatever monster's guarding it," he said.

Rena and the adventurer could feel it too. The strange aura they'd sensed when entering the castle was much stronger here. They were close—very close.

There was no turning back now. Slowly, they walked up to the door.

Unlike the last one, this door didn't need to be pushed. It opened on its own.

What they saw was a massive throne room—spacious, quiet, and looming with tension. At the far end sat a giant man in full black plate armor, holding a greatsword at least five meters long.

Standing beside him was another man—slightly smaller, but still a giant compared to William and the others. He wore cloth robes and held a thick book in his hands.

William's instincts screamed at him.

"Two enemies," he said under his breath. "And they look strong…"

But right near them, shining clearly, was the portal to the next floor of the dungeon.

That meant only one thing: they had to win.

William was the first to step forward, walking confidently into the throne room with power radiating from his body.