Update (15 Jan): The second half of this chapter has been rewritten (Iroha and Yukino's scenes). The first half remains unchanged.

Update (16 Jan): Minor amendments to the dialogue in Yukino's scene

Chapter 4: Under the Gray Skies

Day 3

It was cold, and the skies were grey.

Over the past two days, the temperature had steadily declined, and the sun was a hazy glow in the firmament blotted out by smog. Amidst the summer that was more like fall, the fires had mostly stopped burning, the trees and buildings having been reduced to soot and rubble. Only the stench of charred matter remained, drifting in the breeze from the next city and country over, a smell that would soon be joined by swarms of flies and roaches, relishing in the biggest feast their species had ever seen since the last Ice Age - a stark reminder of the cycle of life and decay from which the apex predators of the terrestrial food-chain were not exempt.

After all, it was not too long ago that strands of protein had formed from the primordial soup, when fish started to walk on land and the bipedal ape-man emerged from the cave to take over the planet. And like so many that had once dominated the tiny blue rock, from the mammoths to the dinosaurs to the ancient anaerobic bacteria pumped into cars and incinerated in power stations - homo sapiens had plunged down the same path of extinction, albeit by their own hands as artificial gods who had flown too close to the sun, having taken so many others to their graves.

Yet, in a high school in the rotten, post-apocalyptic suburb of Chiba, a white-haired young man toiled, working on various devices that he had set out to fix, having scoured the compound for the necessary tools and materials with his acquaintances the previous afternoon. It was surprising what hours of focused and concerted effort could produce in the absence of distractions, and as he turned on the lamps and fans linked to the diesel generators and rooftop solar panels, he could not help but exhale in relief as the others clapped in celebration.

"We'll have to be prudent," he cautioned despite the cheery mood. "Sunlight and fuel aren't plentiful, and excessive illumination and noise may draw unnecessary attention in a supposedly dark and quiet environment."

"At least let us have the air purifiers for ventilation," the fire queen lamented, wiping sweat from her brow. "It's stuffy here with so many people, and the atmosphere is like, radioactive."

"We could switch them on for a while if it makes everyone sleep better," he replied, "I've placed the generators outside so that we won't choke on carbon monoxide, but we'll need to collect more gas if we plan to sustain operations for more than a few hours."

"Tomorrow, perhaps," the blond prince suggested, patting him on the shoulder as he rubbed his sore and aching joints. "We've done most of what we can indoors, but it's getting dark, and an extra day of waiting won't hurt. The intensity of fallout should lessen over time, especially since we've had some rain to clear the sky. We have a few respirators and goggles from the art club, and those should protect us when leaving the building to siphon fuel from nearby vehicles."

"In a desperate situation, we could also mix in filtered cooking oil," the otaku grunted as his stomach rumbled. "But yeah, we'll need to prep the bug-out vehicles and dig a makeshift latrine because some of you are shitting way too much."

"Urgh, don't make me throw up when we're about to have dinner," she spat, folding her arms as a familiar voice crackled through the walkie-talkie, calling them to collect their food.

Shrugging, he strode to the cafeteria with the others in tow, including the dead-fish eyed loner and his group who had grown rather quiet and distant in the past few days. While he had noticed since the first evening, he had decided not to confront them, knowing that not everyone had the privilege of finding their reasons to live on in the intricacies of wires and circuit boards, while attending to more mundane tasks like packing, cooking, cleaning, or taking care of a sick friend.

Nonetheless, morale was important, as was the spirit to persevere in a hellish nightmare, a hostile environment where the ground, air, and water were out to kill them, mercilessly counting down to their demise. It was ironic that having been what others would consider an escapist loser, addicted to anime and manga and wish-fulfilment fantasy while the riajuus went about their practical and meaningful functions in society, he had somehow experienced an awakening when the structures of civilisation collapsed, freeing him of rules to follow and expectations to meet.

For once, he could be anyone and anything - a hero, a saviour, a messiah without being isolated and judged, and there was simply too much to do, to experience, and to achieve before dying.

That was why, even as a part of him felt tempted to join the fujoshi in wasting away on the light novels lining the shelves in a particular section of the library, he spoke as the others ate, mouthing the words that needed to be said. After all, they may have been transported to a brave new reality, but like any good isekai protagonist, it would be their sacred duty to remake the world and forge their own destiny.

"When we're done with preparations, we should start training ourselves in self-defence. I know it's strange coming from me, but it's good exercise and a great way to destress, not to mention we really wouldn't want to be caught surprised when other survivors inevitably run out of supplies and come knocking on our doors or worse, crashing through the gates. Some may ask politely, but many won't be so considerate, especially when they're desperate and famished, with everything to gain and nothing to lose with a few less humans to worry about."

"Besides, if we're ever going to leave this place and venture outside, we'll need to practice while we can, and be ready for any eventuality. We must improve our organisation and refine our teamwork, or we'll be easy targets for looters and marauders along the way. I really don't want to fight, but when it's about what's left and not what's right, what's ahead and not what's behind, we simply don't have the luxury to choose as scavengers subsisting on scraps. Like it or not, the journey for salvation may very well span countless of miles through dangerous territory, and only the strong would prevail, while the weak would–"

At this, the dead-fish eyed loner stood up and left the table. His girlfriend was quick to follow but sat back down as her pink-haired friend clung to her sleeve, pointing at her barely eaten meal. Meanwhile, his little sister looked away, concern hanging over her face, even as she knew better than to step in, giving him the space to deal with the challenges while supporting him whole-heartedly from the side.

"Chuuni-chan, I hear you, but I don't think onii-chan or anyone in the Service Club is in the mood for a pep-talk. Maybe next time, okay?"

Sighing, he picked away at his salad consisting of pickled vegetables and salted fruit, not quite in the appetite despite the hunger. The rest probably shared the same sentiment, stuffing themselves only when the blue-haired kitchen manager chided them for wasting precious food which she and her brother had meticulously laboured to preserve.

Seems like I'll have to do some things myself for now, he noted. Not all deeds are recognised or appreciated until they're needed.

The infirmary was quiet, the silhouette on the bed the only figure in the room. Softly, he approached, careful not to wake her from her slumber as he replaced the wet cloth over her head that was beginning to dry in the heat.

"Senpai," she mumbled, her eyelids fluttering open as she felt the soothing fabric on her skin. Contented, she cast him a reassuring grin before breaking into a cough, her lungs prickling with discomfort just like her neck and much of the surface of her arms and legs. It was a weird sensation, one that she hoped was a figment of her imagination, not that she could really tell in her feverish state. In any case, not wanting to trouble him more than she already had, she would summon her full energy and attention whenever he came to visit, returning to her nightmares only when he urged her to sleep, dreading his absence in the cold, lonely darkness.

"How're you feeling?" he patted her head, careful not to ruffle her hair.

"A little better," she replied - a white lie, just like his strained smile that she both loved and hated to see.

"Iroha," he called her name as he brought out the bento that his little sister had made, "I got you some dinner, wanna eat?"

"Hehe, that won't be enough to sway me. It looks good as usual, but sorry, I can't accept your confession."

"We're still playing that game?"

"You want me to say yes?" she poked him in the cheek, "Maybe when I'm done recuperating. I probably pushed myself too hard running in the rain."

"Yeah," he paused before continuing. "That's why you need to take in more nutrients to keep your strength up."

"I'll consider that if you feed me," she giggled, sitting up to enjoy the glowing shade of red as he fumbled with the cutlery.

Seconds later, it was her turn to blush as he handed her a piece of boiled carrot, which he brought to her mouth with a fork. Not to be outdone, she licked it coyly before swallowing, staring cheekily at the embarrassment on his face. She did it again, more deliberately when he came back for seconds, leaving a thread of saliva and gravy hanging from her lips as she happily munched on the vegetable.

He was wiser the third time around, retracting as soon as she tried to pull her trick, leaving her wide-eyed as he chewed away on the stick.

"That was an indirect k-kiss," she stammered, flushing bright pink.

"Well, we shared a bite," he chuckled. "Maybe that'll teach you not to play with your food. Komachi made this specially for you, and thanks to this, she's been spending more time with him in the kitchen than with me."

"Aww, missing her already? I'd think Kawasaki-senpai would make a pretty good sister-in-law, unless you'd like her to be something more?"

"What're you even saying?" he huffed, scooping her a spoonful of greens, "Here, eat your veggies."

"I'm not a bunny," she pouted as she spotted a glimpse of the raven-haired girl by the doorway, "I'll finish up by myself. It's time to go, senpai, she's waiting for you."

"Make sure you do," he reminded before getting up to leave. "Good night, Iroha."

"You too, Hachiman-senpai," she whispered as the room became quiet once more.

In the tranquil silence, he walked beside his girlfriend as they patrolled the building, shining their flashlights through the empty corridors. She had changed into a spare uniform and a short pair of pants, the sleeves of her blazer and knee-high stockings shielding her from the cold. It was a unique combination, and under the blank sky in the moonless night, she appeared stunning and beautiful, her hair fluttering in the breeze, carefully combed after cleaning up with a wet cloth.

No words were exchanged as they climbed the stairs, treading carefully to avoid shattered glass. Halting before a familiar door, they found themselves hesitating before stepping inside, returning to the place where it had all begun. In the partial darkness, she stood by the window, now an empty void, broken shards mingling with the pieces of porcelain scattered across the floor. For a good long minute, she stared at the pitch-black cityscape, taking in the chilly winds before turning around to face him, a sense of nostalgia and melancholy in her gaze.

"I remember that day like it was yesterday, when Hiratsuka-sensei brought a dead-fish eyed loner to this room. A part of me wanted to keep the club as my private space, but despite the constant insults I threw at him, he'd never quit, and neither did I."

"You sure didn't make things easy," he breathed. "But for better or worse, it all worked out."

"Yeah," she muttered, taking a seat at her favourite desk. "Say, would you have changed anything if you could rewind time?"

"I don't know. Could we have stopped doomsday from happening? Would we have gotten to know each other if I hadn't written a stupid essay? The possibilities are endless, and we can always dream about what could have been. But as much as I dread this future, I don't think I regret the past."

A long silence ensued as she pondered his words.

"Fate is a strange thing, isn't it?" she finally said, "I never told you, but despite our best efforts, my dad just wasn't keen on us being a couple. Nothing against you, but he's convinced that teenage relationships rarely last till adulthood, and he'd arranged for me to study in America after graduation to broaden my options. That future is now past, but if World War 3 hadn't ruined those plans, it could've been difficult for us to stay together."

"I would've waited for you to come back," he replied as she looked away. "Or better yet, study hard to get a scholarship to the States so we'd be free to go out as we please. The universe is a paradox, and reality is absurd and meaningless, but if we push hard enough, life may just find a way through the tangled and intertwined mess of strings."

"Is that true?" she questioned, "If we hoped and wished and prayed, would we be able to have club sessions again? Tell me, Hikigaya-kun, why is it that I'm sitting here, in the room where we're supposed to gather, and yet the air feels so cold that I can't stop my hands from shaking?"

"Yukino," he clasped her trembling fingers, only for tears to stream down her face.

"Why'd we even survive? Do we deserve to live when millions and billions have died? I'm selfish and mean, I've never even properly apologised to you for the incident with my family limo. And yet I'm the leader of our group, I should be strong and responsible, but I'm having negative thoughts, I can barely sleep, I'm haunted by nightmares that we may not wake up tomorrow or make it past the coming week."

"You don't have to do this alone," he cut her short, squeezing her palms, "I'm scared too, and that makes the two of us. Besides, the Service Club isn't just you and me, there's also Yuigahama, Isshiki, and Komachi. Back then, you slapped me back to my senses, so I guess I'll just have to return the favour."

Surprised, she closed her eyes and ducked, only to be greeted by a soft, wet sensation on her cheek. Wanting to scold him for teasing her, she nonetheless found herself kissing back, cuddling in his embrace as he pulled her into a hug, their shadows coalescing as one in the flickering candlelight. It was not their first time making out as a couple, but it was romantic as it was passionate, his lips caressing the crook of her neck as they sat beside the window to the end of the world, his warm breath juxtaposing against the frosty winter night.

"I love you," he assured, pulling away as she panted. "I've never been great at communicating, and I've never actually said the words, but no matter the chaos around us, that has and never will change. We may have lost everything, but we still have each other, and that's good enough reason to live on with nothing. After all, few can claim that their teenage romantic comedy has gone through nuclear fire, but we've endured the flames of hell, so let's persevere and hold on to these precious memories while we strive for a new beginning."

"T-That came off awfully like a proposal," she stuttered as they both turned red. "But thanks for cheering me up."

"Let's head back to the infirmary before they start looking for us," he hastily changed the subject, offering his hand which she promptly took.

It's a promise, Hikigaya-kun, she whispered as she coiled her pinkie around his. We'll do our best to get out of here, and I'll be ready the next time you ask.

Update (15 Jan): This chapter was partly rewritten in response to reader feedback - do let me know if this is better (for those who have read the earlier version) and where I can improve moving forward. As always, favs/follows/reviews highly appreciated!

A/N: Chapter title is a reference to the SI-derived unit (Gray) for absorbed dose of ionising radiation.

I'll be focusing on this fic and the ongoing Five is a Couple (Quintessential Quintuplets, rated M for lemons), but feel free to check out The Holy Grail War of Chiba (Oregairu x Fate), Blessings on This Floating Castle (Konosuba x SAO) and Reality Offline (SAO x Oregairu AU - completed).