Tech Hero in Another World

A few days later.

Somewhere in Japan, inside a modest house belonging to the Asano family, a teenage girl sat frozen in front of her computer screen. The pale blue glow from the monitor lit up her face, highlighting the dark rings beneath her eyes. Her tangled long hair fell across her cheeks, yet her gaze never left the endless stream of news articles, forum threads, and social media feeds she refreshed every minute.

She was Yuuki Asano, the younger sister of Kiriya Asano—the boy who, without her knowing, had been cast into another world. While Kiriya struggled with his new fate in an unfamiliar place, Yuuki was trapped in her own circle of misery in the real world.

Four days… no, it's been almost a full week since I last slept properly, she thought bitterly. Her eyes burned, but she refused to stop. She couldn't stop.

Kiriya was the only true family she had left. Their father had long since passed, and their mother…

Yuuki clenched her fist, nails digging into her palm. Their mother was still alive, but only as a name on the family register. While their father had worked himself to the bone for the family, that woman had busied herself with another man. In the end, she left without once looking back.

Ironically, just days ago, that same woman returned—knocking on their door with a face full of pretended concern. She hadn't come to ask how they were or to show even the faintest regret. Her reason was clear: money.

Three billion yen. The inheritance left by their father. And now, she wanted to reclaim Yuuki, not out of love, but to ensure the fortune fell into her hands.

Even after being driven out repeatedly, the woman kept returning, this time dragging a lawyer along to pressure Yuuki. The girl was alone—no one truly stood by her side.

(Father's relatives are no better. All they care about is money… only Kiriya is real family to me.)

Yuuki let out a long breath, then returned her eyes to the screen. The latest articles on the disappearance of Kiriya's entire class now dominated the front page of every national news site. Blazing headlines in bold letters screamed:

"One Entire Class Missing, Police Still Without Leads!"

"Witnesses Claim They Heard Nothing, Mystery Deepens!"

"Is This a Cult? Or Paranormal Phenomenon?"

But what hurt Yuuki the most was the comment section. Dozens, even hundreds of strangers tossed out cruel words with ease, blaming the school, mocking the missing students as if they were nothing more than statistics.

"Tch… these trashy media can't even hold their filthy tongues!!" Yuuki slammed her fist against the wooden desk in anger.

Her fingers flew across the keyboard, firing back sharp replies at the negative comments. She didn't care if the online flame wars drained her. At the very least, it felt like she was defending her brother—even if only in the digital space.

But the more she fought back, the hollower she felt. Nothing changed. Hatred kept pouring endlessly from thousands of anonymous accounts.

(Damn it… this world is truly rotten.)

Yuuki's eyes shifted to the right side of the screen, where her social media chat window blinked. A new message had arrived. From an anonymous account.

Her brows furrowed. "Huh? Who's this?"

The message was short—just one line:

"For the truth, click this."

Beneath it, a mysterious link waited to be touched.

Yuuki snorted cynically. "What is this… a scam? Or more spam?"

She wanted to ignore it, but something inside her stirred. Strangely, the message was identical to rumors she had once read in shadowy forums—about people receiving "invitations" before getting drawn into unexplainable events.

Her fingers hovered over the mouse, hesitant. If this really is a scam, it could be dangerous. But… what if this has something to do with my brother?

Her heart pounded hard. Fear mixed with a fragile, flickering hope—thin, but real.

"What should I do…" she whispered.

Meanwhile, the computer screen began to tremble faintly, as if responding to her hesitation itself. Then, without realizing it, she clicked the link.

In an instant, black swallowed the screen. Strange text appeared, lines of alien code racing by as though the system was being hacked. Yuuki flinched, panic rising, her hands scrambling at the keys, trying to force an exit—but nothing worked.

"Eh!? What the hell is this!?"

Within seconds, the screen froze. Then a simple symbol appeared: three interlocking gears slowly turning, moving with an eerie harmony.

Beneath the symbol, a single word surfaced.

TECHNO.

Yuuki went still, her whole body locked in place. Somehow, from that simple image, a cold shiver crept down her spine.

"What… is this?" she whispered shakily, her body trembling as the three slowly-turning gears suddenly vanished from her computer screen. Only seconds later, the display shifted into a digital map, a thin green line tracing across before halting on a bright glowing point.

Yuuki's eyes widened. "This location… it's not far from my house." She leaned closer, making sure she wasn't mistaken. "That's the old mansion at the bottom of the hill…"

Her heart pounded violently. That place wasn't just some rundown building—it was the root of countless terrifying rumors. Back when she was a child, her classmates whispered endlessly about the haunted mansion. Some swore they'd seen strange lights flickering through the cracked windows. Others claimed to have heard the cries of children at night.

Yuuki swallowed hard. "What's really going on… Techno…?"

That name echoed in her head again. A memory flickered—Kiriya once sent her a silly meme months ago, jokingly dropping the word Techno. She'd brushed it off as nothing back then. But now, after this message, that memory felt like a deliberate clue.

"Don't overthink it…" Yuuki clenched her fist tight. "If this really has something to do with my brother, I can't just sit around."

The lethargy that had chained her for months—the piles of garbage in her room, her near-hikikomori state—suddenly crumbled away. A new spark of energy surged within her, even if it was wrapped in fear. She hurriedly threw on a gray hoodie and shorts, slipping her phone into her pocket. In her hand, she gripped a small bolt cutter she'd hastily bought from a hardware store.

The walk to the hill took about half an hour. Her steps were brisk, her breaths steady, though her heart thumped in panic. The streets grew quieter the closer she drew to the mansion grounds.

When she finally arrived, Yuuki stood before the tall, concrete-lined gate—still imposing despite its age. Its paint was faded, the iron rusted, yet its air of defiance lingered.

"…I almost forgot." Yuuki exhaled heavily. "I came here once before… to deliver food."

Memories stirred—her father's proud figure standing with his construction crew, his face weary but filled with satisfaction as he built this very gate. Yuuki lowered her head, swallowing the tight ache in her chest. Every detail of this place dragged her back to someone she could never see again.

She raised the bolt cutter, jaws ready to bite down on the old bars, when a soft voice stopped her cold.

"Yuuki Onee-chan?"

Yuuki's body froze instantly. That voice felt as though it had drifted in from another world. With stiff movements, she turned her head. Her eyes widened in disbelief.

"Sui-chan…?"

Bathed in the pale moonlight stood a small girl with long, straight black hair tied into twin tails, her innocent face lit by eyes brimming with curiosity. She was Sui Takamura, the younger sister of Rentaro Takamura—Ren, Kiriya's best friend. Though only eleven, Sui carried an aura that startled Yuuki.

"What are you doing here?" Yuuki asked quickly, trying to hide her panic.

But instead of answering, Sui raised her small phone. The screen displayed something that made Yuuki's breath catch.

It was a map. The exact same map Yuuki had seen on her computer. The same glowing green point highlighting the old mansion before them.

Yuuki's lungs tightened. "You… got that message too?"

Sui nodded slowly. "Yes… a strange message appeared on my phone. I thought it was just a dream. But… then I saw you here, Onee-chan."

The night wind blew harder, rustling the trees around them. Dry leaves scraped across the path, filling the silence with unsettling whispers. The atmosphere grew heavier, pressing on Yuuki's chest, as though unseen eyes were watching them from the shadows.

Yuuki stared at Sui, her heart twisted with conflict. This child shouldn't be here. The mansion was dangerous, steeped in sinister rumors. Yet… how could Yuuki ignore the fact that Sui had been led here by the same clue?

"Listen, Sui-chan." Yuuki crouched down, locking eyes with the girl. Her tone was firm, serious. "This place isn't for kids. You need to go back."

Sui bit her lip, then shook her head sharply. "No! If this is about Onii-sama… I want to know too."

That name struck Yuuki like a blow. Her chest quivered. Even Sui… she too had lost her brother, Ren.

For a moment, silence swallowed them—only the wind and rattling branches filled the air. Yuuki closed her eyes, exhaling long and deep.

"…Fine. But you have to promise me you won't stray far from me. Understand?"

Sui nodded firmly. "I understand!"

Yuuki turned back toward the old gate, her hand trembling as it gripped the bolt cutter. This time, she wasn't alone.

But just as Yuuki was about to cut into the iron bars, the gate suddenly creaked open on its own.

She stumbled back a few steps, her face draining of color. Sui immediately darted behind her, clutching her tightly.