AN: This story started as a prompt given to me by a lovely reader! I loved the idea so much that I couldn't stand to leave it as an one-shot. However, I couldn't only make it Karmanami either, so here you have a character-development based work, whose core is a Karmanami story, with some sprinkles (I won't spoil, but basically more couples, OCs and fluff with a healthy dose of angst).

Each chapter will be named after a chemistry notion (just like Manami, I'm science trash:)). Chapter one is Hydrogene (they will in more cases than not be linked to the meaning of the chapter). Hydrogene is the first element of the periodic table. It doesn't really fit in any group and it's pretty instable all by itself.

Chapter 1: Hydrogene

Manami hopped off the train and made a sprint for the metro station. From the corner of her eye, she caught a glimpse of the digital clock. 16:48, it coldly displayed.

She willed her feet to move even faster, climbing the stairs two at a time. The scientist cursed her lack of exercise- what would Korosensei have said had he seen the terrible shape she was in?

But Korosensei wasn't there anymore. He hadn't been there for the past four and a half years. The simple thought made Manami's heart squeeze.

She barely had time to read the direction of the subway as she turned right in a tight angle, all the while struggling to push the pain that accompanied all the memories of Korosensei somewhere deep down. One would expect her to have gotten over it by now. She doubted she ever would be able of such a feat, though. How could she forget when he had shaped her into who she was now? When it was because of him that she even had the courage to pursue her dream?

Manami managed to jump on the subway just as the doors were closing. She loosed a deep breath once she checked the number and direction were correct and leaned against a pole. She had three stops to catch her breath, before she was going to launch for another crazy run and hopefully make it to Muramatsu's restaurant without getting lost on the narrow streets.

She had missed Kunugigaoka City. Studying kept her in Tsubasa most of the year, and most of the projects brought her to Tokyo. Kunugigaoka, however, was the city she found herself most attached to. It held a special place in her heart and her roots were deeply stuck in this city. Finally having time to spend the weekend here made her smile under her breath.

She got up at her station and tried to persuade her feet into listening to her brain. Sometimes, she really wished she could overwrite science truths such as the accumulation of lactic acid in her tired muscles. She clutched her purse and sped up until she couldn't feel her feet anymore. 16:54, the clock mocked her.

Manami ran as if her life depended on it, trusting her memory to lead her down the right path. A left taken just as she exited the train station, the next right and then another right. A pleasantly lit street opened up in front of her and the buzz of conversation filled the background. Muramatsu's restaurant should have been on the next street to the left.

She hadn't seen her middle school friends in what seemed like forever, although it was only five months. She hadn't been able to make their last meeting during the summer break, because she had scored a spot on a science project and spent the hot months of July and August in the richest laboratory she had ever had the pleasure of laying her eyes on. However, she had seen Kayano and Kanzaki two months ago, when they made a surprise visit to her campus- apparently, Kayano shot a scene nearby- and they always kept in touch.

Manami spotted the restaurant easily- the lights were on and the sound of laughter reached her ears, carried by the autumn breeze. She slowed down, finally feeling the pain in her legs-they were throbbing violently, but she couldn't care less. A wide smile tugged at the corners of her mouth.

She eventually stopped in front of the curtain of the restaurant to straighten herself and wipe the stupid grin off her face. She hadn't realised just how much she had missed her friends.

Manami wiped the sweat off her brow and checked her clock. 16:59, the screen of her phone blinked, making her smirk smugly, as if she had won a bet with time.

She was just about to enter when a voice called her.

"Okuda-san!"

She didn't need to look up to know who had called her. The purring tone was unforgettable, engraved in her mind forever after the countless conversations over the phone they had shared. It was the temptation to see him again made her look to the roof, where a mop of red hair was glinting like fire in the light from Muramatsu's shop.

It took Karma only a few seconds and a well calculated jump to land in front of her. He had grown even taller since the last time she had seen him- when had that been? Eight months ago?

"Karma-kun!" she greeted him back.

He brushed his bangs aside, revealing the golden orbits that hold the key to hundreds of unanswered questions and mysteries. She met them warily, afraid of what would await her there.

They hadn't talked in what seemed like forever. Studies and work had kept them busy, and the once daily calls became weekly, then monthly, then they became random messages and then birthday wishes. They hadn't talked in years. Manami's heart squeezed even tighter than at the memory of Korosensei.

"Don't look so worried, Okuda-san! You know the rooftops are faster," Karma smiled. She didn't know she had missed that smile- his smile- until she saw it. It felt like she hadn't eaten for days, and now that she got a taste of the toffee, her appetite asked for more.

Wiping the grin was impossible after all.

"Should we go in?" he eventually asked, holding the curtain open for her. Manami accepted his invitation and entered without another word to him.

As if words were needed. As if they were ever enough.

The room was brightly lit and mostly everyone was there, gathered around three tables pulled together. The sound of her heels made heads turn, whereas the sound of heavy steps behind her made eyes widen.

"Manami-chaaan!" Kayano called out to her, jumping out of her seat to hug the scientist. She hugged her friend back, trying not to choke from the force of the embrace. From the corner of her eye, Manami could also see Kanzaki approach them.

"Long time no see, Karma," Isogai pleasantly called out, getting up to squeeze his hand. Nagisa was already next to Karma- when did he get there, Manami wasn't sure. "You too, Okuda-san," Isogai added. She nodded from behind Kayano's loving hug, afraid she'd choke on her words if she was brave enough to try speaking.

"Did you guys come together?" Nakamura chimed in her usual mocking voice.

"Just met outside," Karma brushed her off and greeted the others with a nod. He sat down next to Nagisa and opposite a grinning Nakamura. Some things never changed, and that gave Manami a feeling of comfort.

When Kayano finally liberated an exhausted Manami, Kanzaki only hugged her gently and she was finally allowed to take a seat.

Karma patted the seat next to his wordlessly, and Manami took up his invitation. He treated her the same as always, as if the distance between them had never existed. Manami curled her fingers into a fist, creasing the material of her skirt. She missed their easygoing relationship more than she let herself admit.

"And what happened that made you decide to visit us lowly humans?" Terasaka spat his question at Karma. He hadn't attended the last two meetings. In fact, he generally only showed up at Korosensei's anniversary.

"Just making sure my lackey was alive. Now that I've entered university, I'll need someone to do the dirty work for me, won't I?" he smirked.

"Keep dreaming," Terasaka rolled his eyes.

"Oh come on, Rip-off Takaoka. You'll have an easy life if you listen to my commands."

"As if!" the violent boy slammed his fist against the table.

"Easy!" Muramatsu warned, "You're gonna spill the udon!"

"Two more here, chef!" Karma called, pointing towards Manami and him.

"Yes yes, coming," the cook answered before disappearing into the kitchen.

"So, what did we miss?" Karma asked, loosening his tie.

Manami hadn't noticed it while they were in the dim-lit street, but Karma was wearing a full suit, as if he was a real politician. It suited him well, but she prefered the black cardigan- that felt cosier.

"Not much," Kataoka answered. "We were just talking about what each of us had been up to."

"What do you mean not much?!" Maehara protested. "You were just about to tell us how you and Isogai got together!"

"Congratulations!" Manami clapped. She heard Karma hum appreciatively from beside her.

"Oh come on guys, it's not that big of a deal," Isogai waved them off, face on fire.

"Whatever could you possibly mean, class rep? Finding your significant other isn't something to be celebrated for you?" Karma teased.

"You're being overly dramatic, Akabane," Kataoka responded with a glare in his direction, but Maehara seemed to agree with the red head.

"No, Akabane is right," he grinned, "you need to celebrate this by telling us the whole story!"

Nods and excited interjections made the couple give in. And so, the rest of the night was spent slurping noodles and listening to the story of how the two class reps got together, then hearing about Kayano's new movie and Sugino's latest baseball match.

Manami was generally bad with words, but her clumsiness in expressing herself intensified when her feelings were so loud. She quietly indulged herself into the fairytale-like space that the restaurant granted her, cozily wrapped up in her friends' warmth.

Only here, she was still part of the Assassination Classroom.

If not for the hinders of science, she would have claimed that they all travelled back in time. Kayano was still a pudding-addict, Nagisa still kept his hair in twin pigtails, Nakamura still shoved the picture of him kissing Kayano in their faces. And Karma was there next to her too, plotting as always, making fun of Nagisa and winking in her direction from time to time.

Just like the old times.

Only that damned suit Karma was wearing and her hair that hung in a single tail over her shoulder had to remind her that they weren't assassins anymore.

Manami wouldn't have described herself as a sentimentalist, but she did miss Class 3-E greatly. She owed who she was now to her colleagues and to her teachers, that much was obvious to her. She knew her classmates shared similar feelings, and yet, she couldn't help but think they weren't as far away from the assassins they once were as she was.

To start with, Manami had never been a great assassin. Sure she had her fair share of training, but poison and explosives were still her strongest suit. Once she abandoned the rubber blade in her drawer, she stopped being Poison Glasses and started being bland Okuda Manami again.

The scientist loved her new university, she loved chemistry and she loved her life. And yet… she couldn't help but wish to return to her middle school class.

She glanced at Karma, who was mocking Nagisa. He gave off the feeling that time had stopped for him, and his face froze on that mischievous smirk Manami could never forget. Her guts twisted when she thought of how he was in a whole other world from her- as were Kayano, Kanzaki and Nagisa. They each had their own independent lives, universes that barely grazed against each other once every four or five months.

Manami curled into herself, suddenly feeling very lonely.

The clock ticked away with no care in the world, threatening the length of the reunion. Its ticks hurt Manami's ears, tightening those unpleasant knots.

Indeed, the time to say goodbyes came earlier than she was prepared for. She tried in vain to prolong the moment, getting up slowly and taking her time to brush off her skirt. She knew fully well that once she walked out of the restaurant, she'd return to being a normal chemistry student, that she'd have to leave the Assassination Classroom and Korosensei behind.

"Than we'll see each other tomorrow, right, Manami-chan?" Kayano asked with a beam.

Okuda nodded, yet her thoughts were distant. Sure, she'd meet her friends tomorrow, but as regular adults. Not as assassins anymore.

One step on the cement outside the restaurant and the fairytale would dissipate. Manami remembered why she was so scared of reunions-they always came to an end, and they always left a small, empty hole in her heart.

She steeled herself and shook the worries off. In a week, the effect of the reunion would wear off and she'd be back to her normal schedule. 'You can do this,' she told herself, taking a step outside.

The street lamps were blinding.

"Okuda-san!" a voice behind her called, startling Manami. She turned on her heels towards the source of the voice, a glimmer of hope lighting up in her heart.

Karma was leaning against the outer wall of Muramatsu's restaurant, watching her intently from the shadows.

"Are you free right now?"

Manami nodded, putting more energy into it than she thought she had left. She hadn't realised she was wishing for him to say that until the words were fleeting in the dim-lit space between them.

Karma grinned at her. "I was hoping you'd say yes. I have something to talk to you about."

The fairytale wasn't over just yet.