The afternoon sun hung high above the city.
Its warm light stretched across rooftops, train tracks, and quiet residential streets, marking the beginning of a journey neither Yuma nor Serena would ever forget.
For the first time since meeting each other...
Their paths would separate.
Not because they wanted to.
But because they had finally reached the point where each of them had to grow on their own.
Yuma adjusted the straps of his backpack one final time.
The bag wasn't particularly heavy.
A few changes of clothes.
Training gear.
Basic necessities.
Nothing more.
Standing beside him at the front entrance, Alumna checked his watch before calmly slipping it back beneath the sleeve of his coat.
"We should leave."
Yuma nodded.
"...Right."
Behind them, Aunt Melda stood near the doorway with folded arms.
"Try not to break any bones."
"I'll try."
"If you break them..."
She smiled mischievously.
"...make sure they heal before coming home."
Yuma laughed awkwardly.
"I don't think that's how bones work."
"It is if Sensei is training you."
"...Fair point."
Erika handed Yuma a neatly wrapped lunch box.
"I packed extra."
"You didn't have to."
"A mother always worries."
Yuma smiled warmly.
"...Thank you."
Reige stood near his car keys, waiting for Serena.
The house suddenly felt strangely quiet.
Even Stud wasn't making jokes.
Instead, the tiny poltergeist floated toward Yuma.
He crossed his tiny tentacles.
"...My dear boy."
Yuma smiled.
"What?"
Stud looked unusually serious.
"...Don't die."
The simplicity of the words caught Yuma off guard.
"...I won't."
"You promise?"
"I promise."
Stud nodded once.
"...Good."
"...Because if you die..."
His expression immediately became dramatic again.
"...who's going to carry the television?"
Yuma laughed.
"There he is."
"I had you worried, didn't I?"
"A little."
"Excellent."
Before anyone else could speak—
Alumna turned toward the front gate.
"The train leaves in forty minutes."
"Understood."
Yuma adjusted his backpack.
Then turned toward Serena.
Neither of them spoke immediately.
After everything they had said upstairs...
There wasn't much left to add.
Instead—
Serena smiled.
A small one.
"...Don't embarrass yourself."
Yuma grinned.
"I'll try."
"If you accidentally blow something up..."
"I won't."
"...Call first."
"I definitely won't."
"If Sensei throws you off a mountain..."
"...Wait, what?"
"He might."
Alumna remained silent.
Which somehow made the possibility even more terrifying.
Yuma sighed.
"...Please don't give him ideas."
For a brief moment—
Everyone laughed.
The heaviness of parting became just a little lighter.
Finally—
Yuma lifted one hand.
"...See you soon."
Serena nodded.
"...Yeah."
She returned the wave.
"...Come back stronger."
"I will."
Then—
Yuma followed Alumna through the front gate.
The two figures gradually disappeared down the quiet neighborhood street.
Serena watched until they vanished around the corner.
Only then did she quietly whisper—
"...You better."
The train station buzzed with its usual afternoon energy.
Announcements echoed through the platforms.
Businessmen hurried toward arriving trains.
Students laughed together while carrying school bags.
Families gathered near ticket gates.
Everything felt ordinary.
Almost comforting.
Yuma stood beside Alumna while staring at the massive electronic departure board.
"...I've never been to Osaka."
Alumna purchased two tickets from the machine without looking away.
"You'll like it."
"You've been there a lot?"
"It used to be my second home."
Yuma blinked.
"...Because of Dad?"
Alumna nodded.
"...Yes."
The answer carried memories.
Ones he clearly wasn't ready to speak about.
A few minutes later—
The train slid into the station with a low metallic rumble.
Its doors opened.
Passengers stepped out.
Others stepped in.
Alumna walked aboard without hesitation.
Yuma followed closely behind.
They found two seats beside the window.
As the train slowly began moving—
Tokyo gradually disappeared behind them.
Tall buildings gave way to smaller neighborhoods.
Concrete became fields.
The endless noise of the city faded into quiet landscapes.
Yuma rested his forehead lightly against the window.
"...Dad..."
Soon.
Very soon.
He would finally walk the roads his father once walked.
Several hours earlier—
On the opposite side of the city—
Reige's car quietly entered the familiar Yuuki estate.
The large traditional residence stood proudly beneath the afternoon sky.
Stone lanterns lined the pathway leading toward the main entrance.
The family shrine could be seen farther behind the estate, partially hidden among towering cedar trees.
The moment the car stopped—
Serena stepped out.
"...Home."
She hadn't visited in weeks.
Everything looked exactly the same.
Yet somehow...
Everything felt different.
Reige smiled.
"Welcome back."
Before Serena could answer—
A cheerful voice suddenly echoed across the courtyard.
"Serena!"
She froze.
"...Huh?"
The voice sounded familiar.
Very familiar.
She slowly turned around.
Standing near the front entrance—
A young woman waved enthusiastically.
Long chestnut hair reached nearly to her waist.
She wore elegant shrine maiden robes beneath a light cardigan, giving her a graceful yet approachable appearance.
Despite the traditional clothing...
Her bright smile instantly made Serena recognize her.
"...Sis?"
The young woman laughed.
"What?"
"...Did you forget what your own sister looks like?"
Serena's eyes widened.
"...Tamayo?"
The next second—
She sprinted across the courtyard.
"...SIS!"
Tamayo barely had time to react before Serena wrapped both arms tightly around her.
The older sister laughed warmly while returning the embrace.
"There you are."
"I haven't seen you in forever!"
"I know."
"When did you come back?!"
"This morning."
Serena pulled away slightly, still holding both of Tamayo's shoulders as if afraid she might disappear.
"I thought you were still at the temple."
"I was."
Tamayo smiled.
"The mountain shrine still needs someone to watch over it."
She looked toward Reige.
"But Dad called."
Reige rubbed the back of his neck.
"...Guilty."
Tamayo laughed.
"He asked if I could come home for a while."
Serena blinked.
"...Why?"
Tamayo gently poked Serena's forehead.
"...To teach you, silly."
"Huh?"
"The Cybernetic Protocol."
Serena froze.
Tamayo smiled proudly.
"I'm more specialized in our family's Protocol than anyone else."
She shrugged casually.
"So naturally..."
"I said yes."
Serena couldn't believe what she was hearing.
"...You're really going to teach me?"
Tamayo nodded.
"I inherited the temple."
"And with it..."
"...our family's oldest techniques."
She smiled gently.
"If anyone should pass them on..."
"...it's me."
For a moment—
Serena simply stared.
Then—
She smiled.
A genuine, childlike smile she hadn't shown in years.
Tamayo suddenly pulled her into another hug.
"I'm proud of you."
Serena blinked.
"...What?"
"You finally did it."
Tamayo laughed softly.
"You finally survived Dad's overprotectiveness."
Reige sighed dramatically.
"...Everyone keeps saying that."
"Because it's true."
Tamayo grinned.
"I honestly thought he'd keep you locked inside the house until you were thirty."
"Dad!"
"What?"
Serena laughed.
"...I kind of thought that too."
Reige looked betrayed.
"My own daughter..."
Tamayo giggled before suddenly tilting her head.
"...By the way..."
She looked around.
"I heard there was someone else living with you."
Serena blinked.
"...Huh?"
Tamayo continued.
"The boy."
"...What boy?"
"The one Dad mentioned over the phone."
Silence.
Reige slowly looked away.
Very slowly.
Tamayo raised an eyebrow.
"...You know."
She smiled innocently.
"...Your husband."
Everything stopped.
Serena froze completely.
"..."
"..."
"..."
Her face turned bright red.
"...OH."
She had forgotten.
Completely forgotten.
She never told her sisters.
Not one of them.
Tamayo watched her expression with growing curiosity.
"...Wait..."
Her smile slowly widened.
"...You actually forgot to tell us?"
Serena slowly covered her face.
"..."
"...I..."
"...May have..."
"...Forgotten."
Tamayo burst into laughter.
A loud, uncontrollable laugh that echoed throughout the courtyard.
Reige rubbed his temples.
"...I knew this would happen."
Tamayo wiped a tear from her eye.
"My little sister..."
She couldn't stop laughing.
"...You got married..."
"...and forgot to tell your own family?"
Serena buried her burning face into both hands.
"...When you say it like that..."
"It sounds really bad."
Tamayo smiled mischievously.
"...Oh..."
"It gets worse."
Serena slowly looked up.
"...Why?"
Tamayo clasped both hands together excitedly.
"...Because tonight..."
She grinned.
"...You're explaining everything."
Serena's soul nearly left her body.
"...I'm doomed."
Somewhere far away—
On a train speeding toward Osaka—
Yuma suddenly sneezed.
Alumna glanced sideways.
"...Cold?"
Yuma rubbed his nose.
"...No..."
"...I just got a really bad feeling."
Alumna looked back out the window.
"...You'll survive."
Neither of them realized...
That while Yuma's greatest challenge awaited him in Osaka—
Serena's first battle had already begun.
And it wasn't against a Poltergeist.
It was against her own curious older sister.
Night settled peacefully over the Yuuki residence.
The sounds of insects echoed softly from the gardens surrounding the family estate, while warm lanterns illuminated the traditional wooden hallways. Unlike the noisy atmosphere of Yuma's home, the Yuuki household carried an air of quiet dignity.
It had been almost a year since Serena had last spent a night here.
Everything looked familiar.
The polished wooden floors.
The paper sliding doors.
The scent of cedar drifting in from the courtyard.
And yet...
Tonight felt different.
She wasn't returning as the youngest daughter hiding behind her father's protection.
She had returned as someone finally taking her first steps toward becoming a true Geist.
After dinner, the household slowly settled into its nightly routine.
Reige disappeared into his study to organize mission reports.
Erika remained downstairs, preparing tea while chatting with Aunt Melda.
Meanwhile, Tamayo gently nudged Serena with her elbow.
"Come on."
"Hm?"
"Let's go."
"Where?"
"Our room."
Serena blinked.
"...Our room?"
Tamayo smiled.
"The room we used whenever I came home from temple duty."
A nostalgic feeling washed over Serena.
"...I haven't been in there for ages."
"Exactly."
The sisters walked upstairs together.
When Tamayo slid open the wooden door, the room looked almost untouched.
Two neatly folded futons rested against one wall.
Bookshelves filled with old training manuals lined another.
Near the window sat a low table where the sisters had spent countless evenings talking as children.
Serena smiled unconsciously.
"You never changed anything."
Tamayo laughed.
"I was hoping you'd visit more often."
"I've... been busy."
"I know."
The older sister gently sat beside the window.
Moonlight streamed across the floor between them.
For several moments...
Neither of them spoke.
It wasn't awkward.
It was comfortable.
The kind of silence only siblings who had known each other their entire lives could share.
Finally—
Tamayo broke it.
"So..."
Serena narrowed her eyes.
"...That 'so' sounds dangerous."
"It is."
Tamayo smiled mischievously.
"I've missed teasing you."
"I don't."
"I noticed."
The older sister laughed before leaning back comfortably.
"You've grown."
Serena tilted her head.
"...What?"
"When I left for temple duty, you were still chasing Dad around asking him to teach you sword forms."
"..."
"Now you're preparing to inherit our family's Cybernetic Protocol."
Tamayo's smile became gentle.
"I'm proud of you."
Serena looked down.
"...Thanks."
Tamayo folded her legs beneath her.
"Do you know why I'm the one teaching you?"
"Because Dad said you're the best?"
"Partly."
She nodded.
"I'm the third child."
"The others are either stationed overseas, assigned to long-term operations, or guarding other sacred sites."
She chuckled.
"Our family isn't very good at staying in one place."
Serena laughed.
"That's true."
"But..."
Tamayo smiled warmly.
"...Out of everyone..."
"I've always been closest to you."
Serena nodded.
"I know."
"You were still little when I inherited the mountain temple."
"I remember crying."
"You wouldn't stop."
"You disappeared!"
"I had responsibilities."
"I was eight!"
Tamayo laughed.
"You followed Dad around for three days demanding he bring me home."
"...I did."
"You also tried climbing the mountain yourself."
"I almost made it."
"You got lost five minutes from the front gate."
"..."
"...Don't remind me."
Both sisters laughed.
The room gradually filled with warmth.
Hours seemed to pass as they spoke about everything they had missed.
Life at the mountain temple.
Serena's school.
Old childhood memories.
Training.
Family.
Nothing felt rushed.
It was simply two sisters making up for an entire year apart.
Then—
Tamayo smiled.
"So..."
"There it is again."
"Tell me about him."
Serena immediately knew.
"...No."
"Tell me."
"No."
"Your husband."
"He is not—"
"You literally got married."
"It was arranged!"
"So?"
"It doesn't count!"
Tamayo rested her chin on one hand.
"...He's kind?"
"...Yeah."
"Protective?"
"...Sometimes."
"Handsome?"
Serena immediately looked away.
"I didn't say that."
"I didn't ask whether you said it."
"..."
"You hesitated."
"I did not!"
"You absolutely did."
Serena groaned into a pillow.
"I knew this was coming."
Tamayo giggled.
"So?"
"So what?"
"How's married life?"
"We're just living together!"
"And?"
"We argue."
"Mhm."
"He forgets things."
"Mhm."
"He's hopeless."
"Mhm."
"He makes me worry."
Tamayo smiled knowingly.
"...Mhm."
Serena stopped.
"...Why are you smiling like that?"
"Nothing."
"It's definitely something."
Tamayo laughed.
"You've changed."
"I have not."
"You smile more."
Serena blinked.
"...Do I?"
"You do."
"..."
"And whenever you mention him..."
"..."
"...Your expression softens."
Serena quickly grabbed another pillow.
"I am ending this conversation."
She tossed it.
Tamayo caught it effortlessly.
Laughing the entire time.
"Fine, fine."
"I'll stop."
"...Really?"
"No."
"Tamayo."
She finally relented, still smiling.
"Alright."
"I'll behave."
The room became quiet once more.
After several peaceful moments—
Serena looked toward her older sister.
"...What exactly are you going to teach me?"
Tamayo's expression changed immediately.
The playful teasing disappeared.
In its place stood the heir of the Yuuki family's sacred temple.
She looked out the moonlit window.
"...Haikirin."
Serena frowned.
"...Haikirin?"
Tamayo nodded.
"One of the oldest techniques preserved by our family."
"The technique has only ever been entrusted to those who inherit our bloodline's Cybernetic Protocol."
Serena's curiosity grew.
"What does it do?"
Tamayo smiled.
"You'll learn."
"...That's not an answer."
"It wasn't supposed to be."
She stood.
Walking toward a wooden cabinet tucked into the corner of the room.
After unlocking it with a small bronze key, she carefully removed a long wrapped bundle.
Even through the cloth, Serena could sense an overwhelming spiritual presence.
Tamayo gently rested it across the table.
Then she looked back at Serena.
One smile returned.
This time—
It wasn't the smile of an older sister.
It was the smile of an instructor.
"I should warn you."
Serena straightened instinctively.
"When training begins tomorrow..."
Tamayo folded her arms.
"...I'm very strict."
"...How strict?"
"I've made grown Geists cry."
Serena blinked.
"...Seriously?"
"Twice."
"..."
"They deserved it."
Tamayo smiled.
"I'm going to teach you techniques that most Geists will never witness in their entire lives."
"The techniques guarded by our family for generations."
She extended her hand toward Serena.
"So get plenty of sleep."
"Tomorrow..."
Her eyes shone with quiet confidence.
"...your real training begins."
For the first time that night—
Serena felt excitement outweigh her nervousness.
She smiled.
"...I'm ready."
Tamayo smiled back.
"We'll find out at sunrise."