I forgot when was the last time I slept.

I haven't seen her for fifteen years, since that time she allowed her feelings to overflow and let herself cry on my chest. I haven't heard of her, nor had she heard of me since then, since the graduation that peeled off a layer that separated us and yet brought forth a new insurmountable wall between us.

"We could never be together." the woman suppressed her sobs "It's not even our fault, it's just..."

"I don't understand, both of us want to be together, so..."

"Damn right you don't, after all, there's nothing wrong about you."

"Nor about you, why should we be bound by judging voices of those that never even try to understand us?"

A chuckle slipped between her tears "Yeah, that's just like you, always free, bound by no one but yourself." her arms tensed, my arms tightened, and I burried my head in her hair.

"But I can't be like that."

"Shizu-" she released her arms and shook me free.

"Congratulations on graduating, Hikigaya-kun,and may fate let us meet again."

I watched as snow piled up on my window, a cup of coffee sitting cold right beside. No light could be seen beyond the window, it's been late at night after all. Myriad of notes, calculations, and design paper strewn all the way from the base of the coffee cup to the pen on my hand.

Thinking again, I didn't even tell Komachi until I landed in LAX.

I became obsessed with Einstein's relativity in the last weeks before final exam. Pursuing the impossible ideas of reverting time, I went into a frenzy and finished high school with third best grade in my year, the first and second unsurprisingly filled by Yukinoshita and Hayama.

No one, not even my family knew that I took the exam for UCLA until I actually got there. No one knew about the plane ticket I reserved, several trips I took to make the passport and obtain visa. I bought a new phone and a new number out of necessity and only ever called Komachi biweekly, ignoring and sometimes blacklisting the friends and families that were simply worried for me.

For me, the past is something to pursue, not something to indulge in.

"Fifteen." A soft voice came from behind me, from a girl under my supervision that insisted to join me in the pursuit of futility. She suddenly stood up, the paper on her hand still wet with ink.

"Yeah, it's been fifteen years already, huh." the girl frowned, while I spun my chair to look at her work.

"No, sensei, it's fifteen. It's the answer. The Hikigaya constant, it's fifteen!"

"Well, you're the one who found it so shouldn't we call it Eidelfelt constant instead? And stop calling me sensei."

"Flattery would get you nowhere! And it's the answer you sought for last seven years, so shouldn't you be happier?" I sighed

"You miscalculated seventh and twelfth iteration, which snowballs, heh, into next iterations." I picked up her empty cup of coffee and dumped it to the dishwasher. "You should go home and sleep, maybe then you could stop calling me sensei."

The girl pouted, but obeyed me nonetheless.

Her calculation was otherwise perfect, if not for two comma shifts in the aforementioned iteration.

Hikigaya constant, the required reality distortion to turn back time without dismantling matters into primordial energy and glassing an entire city. Of course, the risk it carried means no experiment could be done without knowing the upper limit of how many times we could twist reality, and even then experiment could only be done in a facility on the far side of the Moon.

Ninety Paradox Vertices required to transport a kilogram of matters, with maximum limit of five thousand vertices, limiting time travel to a maximum mass of fifty five kilogram. The universe is more resilient to change than I thought.

I almost felt sorry to the fat old men in the board that wanted to escape reality to the past, but I never cared about them in the first place. On a whim, I stepped to a bathroom scale on the corner of the room.

Thirty eight. That's how much I weight. I suddenly realized I haven't eaten for an entire day, nor has the Eidelfelt girl, and I found myself punching her cell number to the university phone.

"Eh, sensei? Moshee moshee."

"I'm on a good mood so I'll ignore that horrible Japanese impression. Has you reached home yet?"

"Not yet, I have to pick up some groceries..."

"Good, meet me at the Silver Frame in fifteen minutes."

"Eeeh?!" click.

"Cheers for Hikigaya-sensei!"

"Cheers..." Karenina Eidelfelt raised her wine glass jovially while I followed with my cup of coffee, a medium-rare sirloin steak steaming in front of each of us.

"C'mon sensei, this is the achievement of your life! Be more cheerful!"

"We hadn't received the result from LABS and won't be for another week. I'm just treating you as a thanks..."

"Excuses, excuses!" Karenina grinned from ears to ears. "So, you finally have time for yourself, right?"

"What do you mean?"

"You've spent seven years pursuing the secret of time travel, so I think now that you have found at least clue on where to go, you should go out more, meet more people, give a time for yourself..."

"No." I cut through her words. "Not until the theory is complete, not until I could reach..." I sighed, Karenina hadn't moved at all since I started speaking "Listen, Eidelfelt."

She suddenly wolfed down the entire steak, refilled and emptied the wine glass thrice, and left me alone.

Suddenly I felt like burying myself.

I ate the remainder of the steak mechanically, the tender meat tasted like cardboard paper for me (which I could tell from experience). I walked down the empty road to my flat, crashing my body to the bed.

We met again in the study room at the edge of campus building a week later, after receiving the simulation result and permission to do actual experiment. This time, no Eureka moment, no celebratory dinner, only a cup of Earl Grey tea in the now tidy room accompanied by humms of space heater working overtime.

"Mr. Hikigaya," Karenina breached the silence "don't you miss home?"

"I do." I cursed my inability to respond appropriately to her.

"We have a month before the facility come online, why don't you go home?"

I sipped my tea in silence.

"Sensei, kotaete kudasai." She spoke with heavily accented, but arguably better Japanese than the first time she met me.

"I don't know, Eidelfelt." She suddenly rummaged through her bag for a second and pulled out two tickets, with Narita International Airport as destination. I stared with blank eyes.

"Why?"

"No reason. I just felt like dragging you back home."

"I have no one left in Japan."

"Nonsense." She sighed "Komachi-san missed you."

"I don't appreciate you talking to her behind my back..." She stared into my eyes.

"She missed you." Her eyes filled with determination. "Hiratsuka-sensei missed you."

"You know then."

"Yes."

"The reason I wanted to rewind time, the reason I went to UCLA..."

"Yes, and more." I stood up.

"When would the plane departs?"

"In two days."

"Go all the way and pick me up, then." I left her alone, leaving the tea and the smile on her face.

Jetlag was worse than I thought, Japan was colder than I remember, and the airport was less crowded than the last time I was here.

"Remind me not to follow your whims again..." I held my head as I walked through the sparse crowd of fellow travelers.

"Onii-chan!" A girl with disturbingly similar appearance to Haruno Yukinoshita waved to me, and then widen her eyes in a shock "My Onii-chan is walking with a girl!?"

"Aah, sorry for lying, my real name is Karenina, not George." A mischievous smirk adored Karenina's face, her Japanese had become strangely fluent in the space of several days.

"Shock! My Onii-chan has finally become an adult!"

"It's not like that." I rebutted halfheartedly, before hugging Komachi. "I'm home, Komachi."

"Yeah, welcome home, Onii-chan." And then I noticed the woman behind her.

"No hug for me?" She teasingly smirked, and I released Komachi.

"Hiratsuka-san. Long time no see."

"Long time indeed, long enough to find a replacement?"

"Have you?" I subconsciously threw my gaze to her ring finger.

"No, no I haven't."

"Here, Karenina! Let me show you around!" Komachi dragged Karenina away from the two of us, both of them smiling happily.

"Slow down, Hikigaya-san!"

"Komachi is fine!" their voice faded into the bustling airport.

Shizuka smiled again, gently, and this time I'm the one who cried on her arms

Sooo, that's an Oregairu fic for a change. I hope you enjoyed reading it as much as I enjoyed writing it.

I actually wanted to make Hachiman went back in time solely that I could use the line "I've been through infinite universe and fought against time itself just so I could be with you." but then Karenina Eidelfelt showed up and become more than I initially wanted her to be, and dragging the story her way instead of what I wanted it to be...

Eh I dunno, I have never been the best to follow the line I drew myself.

Review is always welcomed. riyangendut out.