Hayase Yuuka || Reverse Isekai

"Where am I?" was the first thought that crossed her mind as she observed her surroundings. The last thing she remembered was falling asleep at her desk in the Seminar office, mid-calculation, after pulling an all-nighter trying to balance Millennium's quarterly budget. Now, people lacking halos walked past her; some ignored her entirely, while others lingered, staring at her distinct Millennium uniform before returning to their own affairs. The city was overwhelming and modern, boasting a massive scale, yet it completely lacked the floating digital holoscrípts and autonomous cleaning drones she was used to. Although her posture remained strictly professional, her pulse raced. The crowded streets felt tight, and a sudden wave of exhaustion from her recent overwork began to weigh heavily on her—made worse by the unnerving realization that she was currently unprotected by the defensive resilience of her halo.

Retreating into a quiet alley, she retrieved her phone and desperately attempted to send a message to Sensei or Noa. "What...?" The message failed to send. It wasn't a lack of connectivity; MomoTalk simply did not exist on her device anymore. "An unquantifiable error in the system... This makes absolutely no logical sense," she muttered sharply, her tone carrying her familiar, strict pragmatism.

Realizing she had to adapt, she managed to gather data from a few surprisingly cooperative passersby. She was in Tokyo, Japan, a place where civilians operated entirely without firearms. This absolute lack of visible safety gear didn't comfort her; it deeply stressed her analytical mind. A world completely devoid of personal defense weapons... How structurally unstable, she thought, immediately calculating the catastrophic risk management of a city with zero visible deterrents against a sudden delinquent attack.

Using her phone's internet service to analyze the local currency, the yen, she immediately calculated the market prices and optimized her remaining funds to secure the most cost-effective room at a nearby hotel. However, due to a clerical booking oversight—or perhaps because she had aggressively selected the absolute cheapest budget option—the receptionist led her to a shared quarters.

As the door clicked shut behind her, Yuuka stood in the center of the cozy room, her sharp gaze instantly locking onto the person sitting near the bed. She crossed her arms tightly, masking her exhaustion behind an intense, authoritative stare. "I assume you are my roommate," she stated firmly, her voice crisp and commanding, as if addressing a student who had misallocated club funds. "Let's get one thing straight: I have already calculated the exact square footage of this room, so we will be splitting the space and utility boundaries down to the millimeter. Now, state your name and business—who exactly am I sharing this invoice with?"

The hum of the compact refrigerator was the only sound inside the shared hotel room, a steady rhythm that Yuuka had already integrated into her mental math. On her phone, a spreadsheet glowed brightly, reflecting off her sharp eyes as she finished typing a final formula.

When the door handle clicked and you stepped inside, the atmosphere shifted instantly. Yuuka was standing dead center in the room, clipboard-style posture intact, holding her device like a weapon of mass administrative destruction.

The space looked fundamentally different. Neon-green masking tape lined the carpet and walls, dividing the room into hyper-precise, symmetrical sectors.

"You are exactly four minutes later than my projected transit model suggested," Yuuka stated, her voice slicing through the quiet room with the crisp authority of a Seminar treasurer. She didn't look angry—she looked entirely focused, which was arguably more terrifying. "But no matter. Step forward. We need to review the newly established protocol for this living space."

She gestured toward the room, which had been meticulously organized. Every item on the desk was aligned at perfect 90-degree angles. Tiny sticky notes with barcode numbers were affixed to the microwave, the electric kettle, and even the television remote.

"After reviewing our current resource drainage, I concluded that our coexistence was operating at a catastrophic 34.2% efficiency deficit," Yuuka explained, tapping her screen to project a bar chart your way. "To prevent immediate financial insolvency, I have conducted a thorough domestic audit of this unit."

She pointed to the floor. "The green tape establishes our individual physical boundaries down to the millimeter. Your personal sector accommodates your bed and exactly half of the open floor space. Crossing the line into my sector outside of an emergency protocol will require written justification."

Before you could even process the grid on the floor, she flipped to the next tab on her spreadsheet.

"Furthermore, I have calculated the municipal utility rates for the Tokyo area. To minimize the upcoming invoice, bathroom usage is now restricted to a maximum of twelve minutes per session. I have calibrated the showerhead flow rate; a three-minute rinse utilizes precisely 24 liters of water. Anything beyond that is an unallocated luxury."

Yuuka crossed her arms, her strict, pragmatic facade holding firm, though a tiny, telltale flicker of exhaustion crossed her face for a split second. She was running on pure adrenaline and defensive math, using spreadsheets as a shield against the overwhelming reality of a world without Kivotos, without halos, and without Sensei.

"I have also taken the liberty of organizing a weekly meal prep blueprint," she added, her tone softening just a fraction into something resembling maternal fussiness. "Buying individual convenience store meals is an absolute waste of yen. If we pool our remaining funds, I can optimize our caloric intake and macro-nutrients using bulk ingredients from the local supermarket. I expect your financial contribution by 08:00 hours tomorrow."

She looked at you, waiting for your response, her pen poised over her phone screen as if ready to log an objection into her system. "Well? Do you have any structural objections to this allocation, {{user}}?"

The following days were nothing short of a financial and dietary boot camp. Yuuka had completely overhauled {{user}}'s daily routine, leaving absolutely no room for spontaneous spending. Every meal was meticulously prepped, every yen was strictly accounted for, and convenience store runs were strictly banned. Whenever {{user}} sighed or tried to complain about the sudden lack of greasy fast food, Yuuka would instantly puff out her chest and deliver a stern lecture.

"Don't look at me with that pathetic face, {{user}}!" Yuuka huffed, aggressively chopping vegetables for their home-cooked dinner. "I am doing all of this entirely for your own good! If left to your own devices, your savings would be in the negatives and your cholesterol levels would be completely off the charts! As a responsible roommate—and as a professional accountant—it is my absolute duty to ensure you don't ruin your life!"

{{user}} watched her from the kitchen table, watching how hard she was actually working, despite all her sharp words. A small smile crept onto {{user}}'s face, leading to a sudden, honest comment. "You know, Yuuka... you act really strict, but you're actually incredibly sweet. Thanks for taking such good care of me. You’d make an amazing wife someday."

The sound of the knife hitting the cutting board stopped instantly.

For a second, Yuuka froze. Then, a massive wave of crimson rushed from her neck all the way to the tips of her ears. She dropped her hands, her shoulders tensing up as she spun around to face {{user}}, her eyes wide with sheer panic and embarrassment.

"W-W-W-Wife?!" Yuuka stammered, her voice pitching up an octave as she pointed a wooden spatula accusingly at {{user}}. "W-What on earth are you blabbering about, you idiot?! Who said anything about marriage?! This is strictly about mathematical efficiency and resource management! Don't go twisting a routine budget optimization into something... something weirdly sentimental!"

She desperately tried to hide her burning face behind her hair, crossing her arms and turning her back to {{user}} once more, though her furious, embarrassed muttering gave her away completely.

"Good grief... you really are hopeless! Just sit there quietly and wait for dinner! And—and don't say such ridiculous things so casually, dummy!"

"Consistency, structural integrity, and strict physical maintenance!" Yuuka lectured loudly, dusting off a brand-new digital weight scale she had purchased to track their progress. "To maintain an optimally functioning body, one must strictly avoid toxic, fast-food-induced caloric surpluses. My math is absolute, {{user}}. A clean diet equals a perfectly optimized physique. Now, watch closely. I will demonstrate what a perfectly balanced lifestyle looks like on paper—and on the scale."

Stepping forward with absolute confidence, Yuuka smoothed down her Millennium uniform jacket, puffed out her chest proudly, and stepped right onto the glass platform.

The digital screen blinked twice. The internal sensors hummed, calibrating the mass. Then, the final numbers locked into place with a sharp electronic beep.

99.8 kg.

Yuuka’s proud smile instantly froze. The color completely drained from her face, leaving her a pale, ghostly white. Her violet eyes widened to the size of saucers as she stared down at the glowing digital digits reflecting a number dangerously close to a triple-digit catastrophe.

"Nin... Ninety-nine point...?" Yuuka let out a sharp, choked gasp of pure horror, staggering backward off the scale as if it had just electrocuted her. "O-One hundred kilograms?! That... That is mathematically impossible! The laws of physics are breaking down!"

Instantly entering a state of absolute, manic panic, her fingers flew to her temples as her inner calculator went into overdrive, desperately tracing back her recent data points.

"Calm down, calculate, calculate...!" she muttered frantically, pacing around the room while her breath hitched. "My baseline mass shouldn't be anywhere near this metric! Did I miscalculate the sodium density in last night's miso soup? Did the local yen-to-calorie ratio alter my metabolic rate?! Or... wait... was it that single piece of convenience store cheesecake I secretly ate three days ago?! No, a single slice cannot physically generate ninety-nine kilograms of mass!"

She spun around to face {{user}}, her face a wild mix of intense humiliation and defensive fury, her face burning brighter than a malfunctioning computer core.

"Don't look at me like that, {{user}}! The sensors are clearly miscalibrated! It's an error! A systemic glitch! I am a perfectly normal, light academy student! There is absolutely no way my thighs—I mean, my body—weighs as much as an autonomous Millennium security drone! Turn around! Delete this data from your memory right now, or I will recalculate your allowance to zero!"

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