Siblings with No Life Get Summoned to Another World as Detectives

Chapter 4: 4. Secret Room & Envelopes



After a long day at school, the brother and sister—Mei and Kai—returned to their new "home." Though… home was a bit of an understatement. The White House looked more like a small castle.

As they walked wearily through the hallway, the carpet muffled every step. When they finally opened the door to their room, they were surprised by a familiar figure—maid Lily was already inside.

"Well…" she said gently, with a curious smile. "How was your day? And… how's the case going?'

Kai and Mei froze. Their eyes met. Silence.

"…The case?" Kai mumbled, blinking in confusion.

.

.

.

"WE FORGOT ABOUT THE CASE!!!" he suddenly yelled.

"Oh no!" Mei grabbed her head.

Lily jumped up and waved her hands to try and calm them down.

"Calm down, calm down! You still have two semesters to find the diary!"

"Two…?" Kai's jaw dropped. "One already passed?!"

Lily nodded. "Yes."

The siblings let out a synchronized sigh, then collapsed face-first onto their beds.

"Is that… a problem?" Lily asked softly, already starting to retreat.

"Please… just go… we're so sleepy…" Mei mumbled, wrapping herself up in the blanket like a burrito.

Lily quietly left without another word, gently closing the door behind her.

A few minutes passed in silence, with the room lights still softly glowing. Then Mei whispered:

"I have a plan."

Kai opened one eye. "I'm listening."

"I'll tell you tomorrow… I need to check something first."

"Alright…" he yawned. "Good night."

"Good night…" Mei whispered, and the room faded into peace.

———————————————————

The next day in the cafeteria during lunch, Kai, Mei, Yuki, and Kitsune sat together, quietly eating. The silence lingered—until Mei suddenly cut straight to the point.

"When is the student council president elected?" she asked, serious and direct, no warning, no intro.

Yuki looked up, caught off guard. Her eyes sparkled for a second with curiosity before answering:

"The submission for applications is still open… why?"

Mei was already on her feet. In the next instant, she grabbed Kai by the sleeve and started dragging him out of the cafeteria.

"Come on, let's go!"

"W-Wait!" he stumbled behind her. "What's the plan now?!"

"Read my mind," she said, not even glancing back.

Kai took a deep breath and whispered, "Mind reading."

Immediately, images from Mei's mind flashed before his eyes. Her inner thought was crystal clear:

"If I become student council president, I'll find someone who knows something about the diary. Success rate: 100%."

Kai paused, thinking. "Of course… She's trying to bait out whoever knows about the diary. That's my sis."

—A few minutes later—

In front of the administration office, Mei was quickly filling out the application form while Kai waited beside her patiently. Once done, she set the paper down on the desk with firm determination.

When they were finished, the two quietly returned to their classrooms. Kai dropped into his seat, still processing Mei's plan.

Yuki was already there in the seat next to him, her head tilted slightly, wearing that faint smile… and a look that said everything.

A look that silently asked: "Do you remember?"

Kai flushed red the second yesterday's memory resurfaced.

"We still have some time before the teacher arrives," Yuki murmured, her mischievous grin creeping in—the kind that always meant trouble was coming.

Before Kai could ask what she had planned, Yuki grabbed his hand and pulled him out of the classroom—their footsteps echoed down the empty hallway as they rushed toward the bathroom.

"Y-Yuki?! Wha—" he stammered, but didn't get the chance to finish his thought.

The next second, the stall door clicked shut behind them. They were close—too close. The space was tight, the air thick with tension. Kai's heart pounded like it was trying to escape his chest.

Yuki looked up at him, her eyes half-lidded, cheeks slightly flushed.

"Just… be quiet for a second," she whispered, before gently—but firmly—placing her hands on his chest… and pulling him closer.

Her lips met his—soft at first, just a brush. But the kiss quickly deepened, growing warmer, hungrier. Yuki pushed him back against the stall wall, never breaking contact. Kai could feel every motion—her fingers curling around his collar, her breath mixing with his.

Then she pulled back—but only for a second. She looked at him with a smile that was both victorious and irresistibly cute.

"Well…" she whispered playfully, "A deal's a deal~"

Yuki slipped out, leaving him alone with his swirling thoughts.

"…What just happened?" Kai said out loud.

———————————————————

3 DAYS BEFORE STUDENT COUNCIL PRESIDENT VOTE COUNTING

The next morning, in the White House.

Kai was lying on the couch, head tilted back, staring at the ceiling.

"I'm bored," he mumbled.

"Me too," Mei replied, sitting on the floor, staring at the wall.

The door suddenly burst open. Lily walked in with fresh sheets, then jumped when she spotted the two of them.

"Ah! You scared me! What are you doing here? Aren't you supposed to be at school?" she asked, shaking out the sheets as she tossed them onto the bed.

"There's no point going until they choose the new student council president," Kai answered lazily, not even glancing her way.

"Oh…" Lily sighed and started making the bed.

Kai's eyes lit up.

"I've got an idea!" he said, suddenly sitting up. "I've already tried my powers… but I haven't seen yours yet."

Mei had already pulled out a small notepad and a pencil. No words.

She started drawing. After a few moments, she'd sketched a knife.

When she extended her hand, a real knife appeared in it.

"Whoa!" Kai leaned forward. "Can you draw like… a gun?"

"No. Too complicated."

"So it has to be simple… What about a boat?"

"Too big."

"Hmmm…" Kai rubbed his chin like some old strategist. "So… not complicated. Not big. I'm guessing no living things?"

"Also complicated."

"Can you summon multiple things at once?"

Mei shook her head. "No. I'm still low level."

She began drawing a cup. The knife disappeared from her hand and turned into a ceramic cup.

"So… they get replaced," Kai observed, examining the cup. "What about your other powers?"

Mei didn't answer. She simply stood up.

———————————————————

They stepped out together into the courtyard of the White House. The ground beneath their feet was calm and still.

Mei took a deep breath and raised her fist.

"SLAM!"

Her fist hit the ground, and the earth trembled.

Kai dropped to the floor with a loud "UOOF!", while the White House gently shook.

"Wow…" he said, still sitting on the ground.

Mei looked down at him from above. Her eyes were cold—but satisfied.

"I'm stronger than you now."

Kai smiled.

"…and I'm smarter."

A moment of silence passed. Then—a smile.

The rest of the day was spent napping and drawing.

———————————————————

2 DAYS BEFORE STUDENT COUNCIL PRESIDENT VOTE COUNTING

Kai and Mei were once again bored in their room.

"I'm bored," Kai mumbled, sprawled across the bed.

"Me too," Mei agreed, staring up at the ceiling.

"Let's go see what Voren's up to!" Kai said suddenly.

His sister didn't answer. She just stood up. That meant she agreed. Together, they headed to Voren's office. Kai opened the door—but the office was empty, so they decided to snoop around a bit.

"How much longer do you want to keep hiding behind these 'masks'?" the brother asked his sister.

"A little longer," she replied, just before she started rummaging through the drawers of Voren's desk.

Kai was searching cabinets, shelves—anything he could get his hands on.

"Yo, check this out!" Kai called, and Mei hurried over to the cabinet he was inspecting.

She gave the cabinet a glance, but then Kai pulled her gently by the hand toward one of those fancy candle holders.

Mei blinked a few times, looked around, and noticed five more candle holders scattered throughout the room. Then she looked closely at the one in front of her—and realized what was off.

"The holder is tilted exactly 1° to the left…" she whispered, and Kai simply nodded, confirming he saw it too.

"What do you think it means?" Kai asked, and Mei simply pulled out her sketchpad and pencil—the two things she was never without.

She began to draw… a feather???

As soon as she finished, it appeared in her hand—a snow-white feather.

She held it high and started walking along the nearest wall.

At first, nothing happened. But then, the feather started to twitch—only near a specific part of the wall.

If she walked past it, the feather stilled again. But when she returned to that spot—it twitched wildly.

This was a classic trick. In a sealed room with no breeze, a feather should remain still.

If it acted like there was a current of air… it meant there was an opening behind the wall. A secret room.

"You found a door?" Kai asked.

"Yep!"

"I knew you could do it!" he praised her proudly.

But then—"So… how do we open it?"

"I'm taking a break from math, and you've got mental cores," Mei yawned.

"Okay… Since there are 6 candle holders, each with 360 possible positions, that gives us exactly...

2,176,782,336,000 combinations.

Meaning brute-forcing it is impossible…"

As Kai was calculating all the possible outcomes and methods for finding the correct sequence, Mei continued inspecting the candle holder.

"Look," she said, pulling Kai toward her.

Engraved on the holder was the word: "FAMILY."

Brother and sister glanced at each other, then began moving around the room, checking the other candle holders.

The words they found were:

FAMILY

FRIENDS

SEPARATION

REUNION

PROMISE

NEW LIFE

"Thinking the same thing?" Mei asked.

"Unfortunately… yes…"

A heavy silence settled over the room. Both of them stared at the floor, and the atmosphere grew somber—maybe even a little depressing.

After a few seconds of stillness, they looked at each other again.

Kai broke the silence with a thought.

"If they've been watching us our whole lives… then maybe they've been recording things somewhere…"

As soon as Mei heard the idea, she walked over to the desk, pulled a notebook from the drawer, and raised it like some kind of divine relic.

"Nice one, sis," he said, patting her on the head. Then he gently took the book from her hands and began flipping through it.

Inside… was everything—literally EVERYTHING.

"Here!" he said, just before a tear ran down his cheek. He wanted to cry—but he couldn't.

Not now—now wasn't the time for that.

Under each "important" event, there was a matching combination from one of the candle holders.

He began reading out loud:

FAMILY — 193°

FRIENDS — 266°

SEPARATION — 15°

REUNION — 289°

PROMISE — 48°

NEW LIFE — 227°

He returned the book to the drawer and shut it quietly. His eyes stayed on the floor.

"…I'm sorry," his sister said softly, trying to cheer him up.

But he had just remembered everything—all the darkness from their past.

They headed toward one of the candle holders—but the office door creaked open, and Vorenhart stepped in.

They exchanged a quick glance, and then Vorenhart spoke.

"Have you two been here long?"

Kai forced a polite smile onto his face before replying,

"We just got here. We were waiting for you, so in the meantime, we were looking at your trophy case."

Vorenhart looked over at the display, then back at them, and smiled. He walked toward the glass case.

"Most of these awards are from before I became president, so they're very important to me," he said, glancing back at them.

"But I know you two have a lot of trophies yourselves. I'm sure you understand the feeling."

"I swear… I wanna punch him so hard. Just try to remind us of one more thing."

That's what Mei thought—but clearly, Vorenhart couldn't read the tension in the air. He simply sat at his desk.

"So… do you need something?" he asked.

"No. Not anymore. We figured it out while we waited," Kai replied smoothly, without letting the fake smile slip from his face—he had mastered that long ago.

The siblings left the office and headed back to their room.

Once inside, Kai sat on his bed. His expression made it clear—what he had read, what he remembered… it hit him hard.

Mei came up to him and whispered softly,

"You can cry."

At her signal, his eyes began to well up.

At first, just a single tear rolled down his cheek—like he was still trying to deny how much it hurt.

But then… another. And another. Until the tears flowed freely, uncontrollably, silently—but like a river that wouldn't stop.

His cheeks flushed, his throat tightened like a stone was stuck in it, and his breathing turned shallow and uneven—every breath like trying to swallow a lump he couldn't spit out.

There was no sound. Just the soft trembling of his shoulders, occasionally jerking—like his whole body was crying in silence.

His hands clenched into fists, nails lightly digging into his palms, as if trying to hold himself together—but the tears were stronger.

Mei gently pulled him into her arms, and his head dropped onto her shoulder.

That's when the sobs turned quieter—but deeper, heavier, as if every part of him was screaming without a voice.

That hug was like an anchor in the middle of a storm—the only place he could fall apart…

and still find himself again.

———————————————————

1 DAY BEFORE THE STUDENT COUNCIL PRESIDENT VOTE COUNT

Kai and Mei were, once again, bored in their room.

"I'm bored," Kai mumbled, lying on the floor.

"Me too," Mei agreed, sprawled across the bed with her head hanging off the edge of the mattress, staring at the floor.

Silence.

"Let's go to school today," Kai suggested.

"But... the election is tomorrow," Mei protested, not wanting to go.

"I know, but isn't it more fun there than here?" Kai asked, not taking his eyes off his sister.

"Maybe... But I hate school. And… there's no one special there," she replied.

Kai had no response, but he wanted to ask the same question from yesterday.

"How much longer are we going to hide behind these 'masks'?" he asked.

Mei didn't answer. She just stood up and grabbed her school uniform.

After a few minutes of getting dressed, they headed out for school.

The walk was short, and when they arrived, the school gates were open. Voting was still ongoing.

"There's no point in voting…" Kai muttered. "You're going to win anyway."

Mei simply nodded.

They kept walking—each toward their own classroom.

———————————————————

When Kai entered his classroom, his eyes immediately landed on Yuki.

She was already sitting at her desk, quiet as always, with her hands folded neatly on the table.

Without a word, he sat down beside her.

"Hey," he said softly, with a gentle smile.

Yuki didn't respond right away. She simply pulled out a small envelope and slid it across the table to him.

It was yellow, with a tiny red heart stuck right in the middle.

Kai raised an eyebrow. "What's this?"

"I haven't opened it," she said calmly. "It's been sitting on your desk since yesterday."

His gaze dropped down to the envelope.

———————————————————

Mei stepped into the classroom, her eyes briefly scanning the room before she silently took a seat next to Kitsuna.

Without warning, she reached out and gently began stroking Kitsuna's ears, her fingertips softly tracing along the edges.

Kitsuna closed her eyes and quietly… began to purr.

Prrr...

"This was on your desk," she murmured, pulling a small envelope from her bag—yellow, with a red heart in the center, identical to the one Kai had received.

Mei glanced at it briefly.

Then took the envelope.

———————————————————

Kai and Mei sat in separate classrooms, far apart from each other.

But something… something invisible tied them together.

At the exact same moment, they opened their envelopes.

The paper rustled softly beneath their fingers as they pulled it out.

Their eyes drifted down the handwritten words.

"I'll be waiting behind the school after class."

They closed the envelopes at the same time.

———————————————————

"I expected them to send us something like this later… isn't it a bit early?" Kai muttered as he stood up and walked toward the trash bin.

The envelope was already crumpled in his hand.

Yuki stared at him, surprised.

"Wait… you expected it?" she asked.

Kai simply shrugged without looking back.

He tossed the crumpled envelope into the bin nonchalantly.

"Some games always start before the official match," he said quietly.

———————————————————

During lunch, the brother and sister talked as if everything was normal—they didn't even mention the envelopes. At least not until Kitsuna reminded Mei.

"What are you gonna do about the love letter?" Kitsuna asked.

"Love letter? Huh? You got one too?" Yuki asked her, before continuing, "Kai got one as well."

"Oh… That…" Mei started, but her brother finished the thought for her:

"Nothing. We'll just see what happens," Kai replied.

"…" Mei nodded in agreement.

For a moment, it seemed like the topic had ended. But then…

"Of course… you can always reject her," she said, her eyes glinting with something dark, twisted. Then she tilted her head to the side, her smile growing wider.

"Because in the end… you're mine, aren't you?"

Kai subtly leaned back. Swallowing hard.

Mei lowered her gaze to her plate, deep in thought.

"But why would they call us to the same place, at the same time? Coincidence? I don't think so," she pondered.

———————————————————

After the final school bell rang, Mei and Kai met in front of the school gate, ready to head out together to meet their supposed crushes.

"Ready?" her brother asked.

She didn't reply—just gave a quiet nod.

They walked around the school building and stepped into the shadows of the back courtyard. There, a boy and a girl were waiting for them—looking eerily alike. They didn't seem nervous at all, which was already suspicious.

"Hello! My name is Vex!" said the boy, with a wide but entirely unnatural smile.

"I'm Lilith!" the girl chimed in, wearing the exact same smile.

Kai and Mei exchanged a glance. That single moment of silence was enough.

"A trap," Mei muttered.

And then came the footsteps—from both sides.

From the shadows, five students stepped out, surrounding them in a circle.

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