The bus slowly traveled along the dark road.
The cabin lights were turned off, leaving only the dim glow of the emergency lights along the aisle.
Most of the students and teachers were already asleep. Others were busy using their phones or listening to music.
In a window seat, Airi was asleep, her head unconsciously resting against Nanao's shoulder.
Her breathing was steady, and her face looked tired but peaceful.
Nanao was still awake.
He glanced to the side, looking at Airi.
He didn't move his shoulder, not wanting to wake her.
From the seats behind them, a few whispers could be heard.
Hana leaned forward.
"Hey... look."
Luna gave a small smirk.
"Seriously? She's leaning on him like that?"
Rina tried to hold back her laughter.
"She's pretty bold."
Hana half stood up, pretending to reach for something, then deliberately flicked Airi's ponytail.
Airi moved slightly and frowned in her sleep.
Nanao immediately turned around.
"Hey."
Hana pretended to be innocent.
"Oh, sorry. I thought it was my bag."
Luna joined in and tapped the back of Airi's seat.
"Wake her up. Poor thing fell asleep."
Airi slowly opened her eyes.
"Hm...?"
Nanao immediately sat up slightly, his voice cold.
"Don't bother her."
Rina chuckled.
"Why? You're being pretty protective."
Hana grinned.
"Or maybe... she's your girlfriend?"
Airi immediately woke up completely.
"What—?"
Nanao answered without hesitation.
"She's my little sister."
Hana's eyes widened.
"WHAT?"
Luna narrowed her eyes.
"She's your sister?"
Rina laughed sarcastically.
"She doesn't even have a family. What are you talking about?"
Nanao looked at each of them.
"No. Now... she's officially my adopted sister."
His tone was firm.
"And if you bother her, I'll be the one standing up for her."
Hana clicked her tongue.
"Wow. Just because she's an orphan, you decided to take her in."
Airi fell silent.
Her hand clenched the edge of her shirt.
Luna smirked.
"What's the point of making her your sister anyway?"
Rina added,
"She's useless. What's the point?"
Nanao clenched his fist.
"And exactly how useful are you to be looking down on her like that?"
Luna laughed softly.
"I'm already sure our futures will be bright. Unlike your adopted sister."
Rina nodded.
"I'm sure nobody would want to be friends with her anyway."
Hana concluded mockingly,
"Poor Nanao. Hanging around with someone this stupid."
Nanao turned toward Airi.
A tear silently rolled down her cheek.
Nanao let out a long sigh.
"Enough."
His voice was low but sharp.
"We came on this study trip to have fun. Not to listen to your nonsense."
Hana scoffed.
"Fine. Whatever."
She yawned.
"We're going to sleep."
Hana, Luna, and Rina slowly returned to their seats and lay down.
The bus became quiet again.
Nanao slowly sat down and turned toward Airi.
"Are you okay?"
Airi nodded slightly.
"I'm okay... I think."
Nanao softened his voice.
"You can go back to sleep."
Airi lowered her head.
"I'm sorry, Big Brother... Because I fell asleep on your shoulder, you ended up arguing with them."
Nanao smiled bitterly.
"I actually feel like I lost that argument."
He looked forward.
"As your big brother, I should've been able to protect you better."
Airi turned toward him, her eyes still wet.
"It's okay."
She gave him a small smile.
"Just being my big brother like this... already makes you the best big brother I could ask for."
Nanao fell silent.
Then, slowly, he shifted his position slightly—
blocking Airi from the direction behind them.
"Just sleep," he said softly.
"I'm here."
Airi closed her eyes again.
And this time,
she fell asleep feeling safe.
---
The bus continued through the night.
The constant hum of the engine slowly made the atmosphere more peaceful.
Airi was completely asleep this time.
Nanao remained awake.
His eyes were fixed on the window as the streetlights passed one after another, appearing like broken lines of light.
His arm remained along the side of the seat, deliberately blocking the space behind them—as if he were acting as a protective barrier.
Several minutes passed.
Suddenly, the bus slowly came to a stop.
"Everyone," the teacher's voice came from the front, "we're going to stop at a rest area for a while. Fifteen minutes. Don't wander too far."
Several students immediately woke up.
A small commotion filled the bus.
Nanao turned toward Airi.
"Wake up."
Airi slowly opened her eyes.
"Hm... Are we there already?"
"Not yet. We're just taking a break."
Airi nodded and slowly stood up, still a little unsteady from sleep.
When they got off the bus—
Hana, Luna, and Rina were standing not far from the door.
Hana crossed her arms.
"Wow, you two are still sticking together."
Nanao immediately stepped slightly forward.
"Is there a problem?"
Luna smirked.
"Relax. We're just surprised."
Rina looked Airi up and down.
"No wonder she's comfortable. She's got a bodyguard."
Airi lowered her head.
Her hand instinctively grabbed the edge of Nanao's jacket.
Nanao noticed.
He turned toward Airi.
"Do you want to use the restroom or get a drink?"
"A drink..." Airi replied softly.
"Alright. I'll come with you."
They walked away.
Behind them, Hana whispered irritably,
"He's acting so tough."
Luna narrowed her eyes.
"Relax. The study trip is still long."
---
Inside the rest area's convenience store, the bright lights were almost blinding.
Airi stood in front of the drinks section, looking confused.
"Which one do you want?" Nanao asked.
"Just this one," Airi replied as she picked up a bottled tea.
Nanao took another bottle and paid for them.
When they sat on a bench outside—
Airi slowly turned the bottle in her hands.
"Big Brother..."
"Hmm?"
"If they say something again..." Airi hesitated. "You don't have to defend me."
Nanao quickly turned toward her.
"Why?"
Airi gave him a small smile, but her eyes looked sad.
"I don't want you to become their enemy just because of me."
Nanao was silent for a moment.
Then he spoke firmly but calmly.
"That's exactly why I can't just stay quiet. You're my sister."
Airi looked at him.
"The world has already been cruel enough to you," Nanao continued. "I don't want to become another person who makes things worse."
Airi lowered her head.
This time, it wasn't because she was sad.
"...Thank you, Big Brother."
A few minutes later, the teacher called the students back to the bus.
During the next part of the journey, Airi sat upright.
She didn't fall asleep again.
But this time—
it wasn't because she was afraid.
It was because, for the first time...
she no longer felt alone.
---
The bus finally stopped in front of a large lodging facility.
The garden lights illuminated a three-story building with a spacious courtyard in front.
"Everyone, get off in an orderly manner," the teacher said while standing near the entrance.
One by one, the students got off the bus with their bags.
The night air was cool and slightly humid.
Airi stood beside Nanao, hugging her backpack.
She stared at the building with a mixture of amazement and nervousness.
"It's pretty big," she murmured.
Nanao glanced at her.
"Is this your first time staying somewhere with this many people?"
Airi nodded slightly.
"Yeah."
The teacher spoke again.
"Now, we'll assign the rooms. Two to three students per room."
Several students immediately started talking, calling out their friends' names.
The teacher looked at the list.
"Nanao... you'll be sharing a room with—"
Before he could finish—
"Sir," Hana said while raising her hand, "aren't boys and girls supposed to stay separately?"
Several students nodded in agreement.
The teacher sighed.
"Don't worry. I know. That's why—"
He looked at the list again.
"Airi will be staying in a room with the other girls."
Airi fell silent.
Nanao immediately turned toward her.
"Airi—"
"It's okay," Airi said softly, forcing a smile.
"I can handle it."
The teacher continued.
"Airi will share a room with... Hana, Luna, and Rina."
Silence.
For a moment, several students looked at one another.
Nanao immediately stepped forward.
"Sir, can't you change the arrangement?"
Hana gave a small smile.
"Why? Are you scared?"
The teacher looked at Nanao.
"This is only a temporary arrangement. There aren't any other rooms available."
Airi gently tugged on Nanao's sleeve.
"Big Brother... I'm okay."
Nanao looked at her for several seconds before slowly nodding.
"If anything happens, contact me immediately."
Airi nodded.
---
The room was on the second floor.
As soon as the door closed—
Hana threw her bag onto the bed.
"Well... looks like we're sharing a room."
Luna slowly closed the door.
"Seems fun."
Rina sat on the edge of the bed and crossed her legs.
"Don't get too excited. We just happened to get assigned to the same room."
Airi stood near the door, unsure where to go.
Hana looked at her.
"What? Are you scared?"
Airi shook her head.
"No."
"Good," Hana said flatly.
"Rule number one in this room—"
Luna smirked.
"—don't get too close to us."
Rina added,
"Rule number two: don't tell Nanao anything about what happens here."
Airi looked down.
"I wasn't planning to—"
Hana interrupted.
"Rule number three..."
She stepped closer.
"Don't use the fact that you're an orphan to get sympathy."
Airi clenched her fists.
But she took a breath.
"I just want to get through this study trip peacefully."
There was silence for several seconds.
Luna gave a small laugh.
"Peacefully? You picked the wrong room."
---
The night grew late.
The room lights were turned off, leaving only a small bedside lamp.
Hana, Luna, and Rina were already lying down.
Airi sat on her own bed, hugging a pillow.
She stared at her phone screen.
A message appeared.
Nanao:
Are you okay?
Airi slowly typed a reply.
Airi:
I'm okay. Don't worry.
She turned off the screen and lay down.
Under the blanket, her eyes remained open.
She stared at the ceiling.
For the first time in a long while, Airi realized—
this wasn't only about being bullied.
It was about how strong she could become...
without always having to hide behind someone else.
In another room, Nanao stared at his phone for a long time.
"...Don't try anything," he muttered softly.
And that night,
the peace only lasted on the surface.