It taken over twenty years—twenty years of mind-bending science that Senku still wasn't quite sure he understood—but they had finally done it.

The time machine was done, much quicker than anyone had anticipated.

It wasn't what they had expected, but that was kind of how science went. They had consistently failed to send back any kind of physical matter, so the dream of sending someone or something back was a no-go. Information was their medium of choice.

Also, they couldn't reach their own past. Theories were being thrown around about alternate timelines and dimensions and diverging pathways, but the truth of it was this: they could only communicate with one alternate version of themselves, in what seemed to be a nearly identical timeline.

The trouble with sending back information a few thousand years (well, one of the troubles) had been that there wasn't specialized equipment to receive their messages in the past. It had taken years of fine-tuning to even get what was basically a video conference with the recent alternate past.

Another was the sheer amount of energy it would take.

Another was who to contact in the first place.

The project had been worked on in what was essentially overlapping shifts. People would work for a year, contributing ideas, and then take time off the project, maybe a year or two. It was necessary—it wasn't healthy to focus on one project for so long. And it wasn't like they were being paid for this. It was strictly volunteer work. (Although Ryusui usually found other ways to incentivize things.)

Now here they were, ready to try and do the impossible.

Senku cleared his throat. "Call crew here. All clear."

The rest of the team sounded off, "all clear" echoing over and over: the engineers on the power grid they'd developed, the technicians with the equipment, the other scientists on standby ready to overcome any obstacle they faced, all these people all over the world ready to help stop a thousands-year-old disaster.

It sure was something. Senku looked over at Suika. She had on the thick, watermelon-patterned glasses she had started wearing in her twenties and a lab coat. Her hand hovered over one of the switchboards, ready to get to work when given the signal. When she felt his gaze, she made a face at him and he smiled.

Chrome was with the technicians. Senku knew Ruri, Taiju, Yuzuhira, and many of their friends would be hanging out in another part of the facility for moral support.

Why-man was also with the technicians—if something really went wrong, it would be able to help. Hopefully, nothing went wrong.

It was…weird. Senku swallowed and looked back to the computer and camera set up in front of him. Time had raced by, it seemed. Wasn't it just last week he was watching his dad head off to the ISS? Wasn't it just yesterday he himself had impossibly walked on the moon?

But no, he was almost fifty now. (Older than his dad had been the last time he'd seen him.) His jaunt to the moon had been half a lifetime ago. His friends' kids, who all called him Uncle Senku, were becoming adults, figuring out what they wanted to do with their lives, finding their paths, and it was awesome and scary and honestly kind of heart-breaking, in a good way.

And now he might get to talk to his dad again.

If everything went according to plan.

They'd decided to try to reach the Senku Ishigami of the late 2010s, for the simple reason that the Senku Ishigami of the 5760s was the only person that remembered his old IP address and security measures and whose past self had the capability to do something about the impending petrification of the planet.

Their date was set: January 1st, 2018. That would give them more than a year of communicating with little Senku, and thus hopefully Byakuya and his scientist colleagues. With the science and facilities available in the past, that should be more than enough time to put the plan they'd come up with into action. The team was optimistic about the success of the call, more or less; the initial power required to make the connection would be incredible, but if they were able to keep the connection steady, the power grid should be able to handle it. They'd run simulations on getting to Senku's computer very quickly with success. They might be able to make this work.

It was also generally accepted that this was a one-shot deal—the tech required was fragile, temperamental, and costly, and probably wouldn't make it for a second call. It was this or nothing, so they had to make it work.

The final "all clear" rang out from the comm system. There was a pause, heavy with anticipation. Senku heard Suika take a deep breath and mutter something to herself. He closed his eyes and counted the seconds, waiting for control to give the go-ahead.

One.

Two.

Three.

"Tech crew, please begin connection startup."

"Copy that. Beginning connection startup."

Here we go.

Ishigami Senku, scientist and student, was at his computer (a typical place for him to be). He was reviewing his rocket blueprints, this time with an eye towards testing a more efficient way to get astronauts onto the ISS—the current journey lasted anywhere from six hours to two days, and there was definitely room for improvement. It wouldn't be done in time to benefit his dad, but he might finish in time to benefit himself.

He had just saved a new page of notes when something started connecting with his computer. Startled, he went to cut the internet, but whatever had hacked him was fast—and apparently knew his name.

"Ishigami Senku," read the chat window that popped up. "We need your help."

And that was enough to make him pause. Scams often requested help, like a person pretending to be a grandchild in trouble, but it was a bit weird that someone had hacked their way into asking for his help, especially into a computer like Senku's (he was pretty good at cyber security, he thought, but apparently not good enough). It was enough to pique his curiosity.

He checked some things first, though, glad he'd disconnected his backup drive. Nothing was happening in the background—no sneaky traffic or downloads or uploads. It was…just a chat window, it looked like.

So, even though he knew it was probably a terrible idea, he clicked on the window.

Nothing happened, except for a blinking cursor.

"You've got a funny way of asking for help," he typed back.

The response was quick: "There wasn't another way."

And then, bizarrely: "Can we turn on our video?"

"Why?"

"Easier to talk."

Senku looked around his room, sort of wishing his dad was here. Or even Taiju or Yuzuriha.

"Ok," he typed, knowing he was being incredibly stupid but too curious to say no.

A video loaded—and Senku was looking at himself.

Or, rather, he was looking at an older version of himself.

The older version of him gave him a grin. "Hi, little me. I know it's you, even if you don't start your webcam. Don't worry, we won't hack it."

Senku wasn't sure what to say, so he didn't type anything in response. A digital facial reconstruction program, maybe? One of those aging software programs with some facial movement recognition? How had they gotten the voice right?

"First off, before anything else, could you tell me the date?"

Frowning, Senku typed, "June 1, 2019."

And the video of his older self went pale and sat back, rubbing his hand over his mouth. "June 1st. 20…19. Well, that's not…ideal."

"What?" came a screech from off screen, and then a woman with green glasses was grabbing the collar of his older self's lab coat, shaking him. "2019? June? We have less than a week! That's a couple days!"

Older Senku pulled her hands off his collar. "Suika, I know, calm down."

The woman ran off, screaming for someone else, and Senku heard a door slam open. and a roar of voices shouting before the door slammed shut again, cutting the shouts off.

Older Senku, meanwhile, seemed to have aged an additional ten years in less than a minute.

What was going on? What kind of hoax was this?

"Senku," said the older man. "I don't know how to…hm." The man rubbed his forehead with a trembling hand, deep in thought. Finally, he sighed, ran his hand through his hair, and muttered, "Ok. So it's a worst case scenario. That's…fine. We'll do our best anyways."

And that, more than anything, made Senku think he was maybe looking at a future version of himself. His dad's motto wasn't inherently unique, but the momentary soul-deep look of despair combined with the phrase and then that limitless determination was terribly familiar. Didn't he always have the worst luck? Didn't he always push through anyways?

So, if he was accepting that time-traveling video calls existed, why would a future version of him risk calling the past? Something must have gone horribly wrong, something devastating enough that he believed the immense risks and costs of time travel were worth the possible benefits.

It seemed like there was a support team in the background, if the noisy crowd he had heard earlier meant anything, so it had probably been a widespread, maybe worldwide event. If he had to seriously consider it, Senku wouldn't even try to reach out to the past unless more than seventy-five percent of humanity had been wiped out by something preventable.

Which meant the tired, thin, frazzled man on his screen had been through something like hell, was trying to fix it, and the planned time frame to try to save the world was shot. A couple days, that woman had said. A literal deadline.

It might be a hoax, yes. But Senku would rather be made a fool of while trying to help than be the kind of man who refused to help save people's lives for fear of looking stupid.

He turned on his video. Older Senku looked surprised.

Senku crossed his arms and said, "How can I help?"

Byakuya wasn't expecting a call from Senku, even if he hoped for one. Not that he'd ever tell Senku that. His teenager would make a face and groan about maudlin parents and then refuse to call him for a month on principle.

Which was one reason he was so surprised when there was a call from Senku waiting for him when they docked with the ISS, and why he answered so quickly. Senku wouldn't call before their scheduled time (a week from now) unless something was wrong.

(He completely forgot about the prank he and Lillian had planned in the final days of their training. Lillian, feeling unsettled by the normally cheerful man's obvious concern for his son, introduced herself to the rest of the crew normally, then slowly scooted so she was hovering nearby Byakuya to make sure everything was okay.)

He turned on the video call quickly, tapping his fingers against his arms impatiently as it connected. "Senku!" he cried as his son's webcam finally loaded. He quickly scanned his son's face—his kid looked stressed, his already unruly hair even messier, sticking out to the sides as if he'd been pulling on it. "What's going on? What's wrong?"

His son opened his mouth, then just sighed. "Hi, dad. How's space?"

Byakuya frowned. Senku didn't tend to dodge direct questions unless he was extremely stressed. "Awesome. Obviously. Seriously, though, what's wrong?" He was mentally running through responsible adults he could call to check on Senku. Yuzuhira's parents, the Ogawas, were probably his best bet. He had some work colleagues he could reach out to if they weren't available, though.

Senku groaned. "Oh, this isn't going to get any easier. Sorry, dad." His son clicked something, and then a second video was loading up. Byakuya frowned—how had he managed that? And then he was looking at another video of Senku.

But it was not his Senku.

The man on the second video was, if possible, even more stressed-looking than his son. He was much older-looking as well. Byakuya was confused—had Senku made some new simulation software? His son wouldn't think that itself was worth a call.

The second video also seemed to be buffering or something, the older-looking Senku staring straight ahead with wide eyes and barely moving.

Byakuya focused on his son, deciding that he needed to be even more direct. "Senku. Please tell me what's going on. Are you hurt? Are you in trouble? Do you need to go to the hospital, or do you need an adult with you? I can call the Ogawas to come check on you, or you could stay over with them. I'm sure they wouldn't mind. Or you can have Taiju come stay with you, his guardian would be okay with that." ISS control might have a policy of family-only calls, but there was obviously something wrong with his kid, and control was made up of humans, too—they'd understand if Byakuya needed to ensure the wellbeing of his son.

While he spoke, the older-looking Senku had rubbed his eyes, then leaned back and said something that was inaudible to the computer's mic. His Senku rolled his eyes. "I'm good, I promise. Don't get all worked up."

Byakuya wanted to shout that he was obviously not good. He didn't, of course. But he wanted to.

And then an older Taiju and Yuzuhira were on the screen with the older Senku. Senku seemed just as surprised as Byakuya was.

"Oh my gosh," said Yuzuhira, tears pooling in her eyes. "It's really you."

"Old man!" cried Taiju with a laugh. "Wow, it's great to see your face again! And little Senku!" Older Taiju grabbed the older Senku in a headlock and ruffled his hair. "Aw, look at that little baby face!" Yuzuhira giggled as the older Senku struggled to push Taiju away.

"Get off me, you big oaf!"

It was a scene Byakuya knew well, but it was wrong. The kids he knew—but as old as he was. Older, even.

"Thanks, Senku," Yuzuhira said quietly, putting her hand on Senku's shoulder as he tried to fix his hair. Senku smiled fondly at his two friends—and when had Byakuya ever seen Senku smile fondly at anything? "We'll leave you to it." She waved at the camera. "Good luck, you guys! If anyone can do this, it's you!" Then she pulled a tearing-up Taiju out of view.

Byakuya stared at the older version of Senku. It was his son—the way the man sat, the mischievous smirk on his face hiding the fact that he was scared—but Byakuya still didn't understand.

The noise had attracted the attention of the other five occupants of the ISS. There wasn't really "privacy" up here, was there?

"Alright," older Senku said at last, speaking in English. "This won't get any less confusing, so let's press ahead. First off: hi, dad. It's really good to see you again. Second: your world is about to end and we have to stop it."

Byakuya shook his head. Was this a prank? Senku wasn't into elaborate pranks, especially not when it came to actual work or school. Surprises, yes, but not pranks.

"If I remember correctly, there should be a high-quality telescope on board the ISS," the man continued. "This is the best way I can think of to show you what's going on. I need someone to take that telescope and point it to these coordinates on the moon." A set of coordinates popped up in the chat.

"Please," older Senku said when nothing happened at first. "Please, just do this. If there's nothing there, fine, but I need to know if there is." He sounded…desperate.

Byakuya turned to the rest of the crew. "Well, I don't suppose any of you know moon coordinates?"

Baffled and a bit exasperated, the crew set up the telescope. They were in luck—the moon was currently visible to them. Shamil manned the telescope, muttering about teens and TikTok, but then abruptly stopped. "What?" he whispered, looking at the moon outside the station viewport before peering back through the telescope viewfinder.

"Is something there?" Darya asked, surprised.

Shamil gestured to the telescope and pushed himself back. "Look. Look for yourself." Everyone did so, and so everyone saw it—a swirling mass of black, moving, shifting, on an otherwise barren moon. Even Lillian looked, morbidly curious.

"It's a black cloud, right?" older Senku said. "Big, ominous, swirling around. I don't know how big the diameter would be then, but it looks like a swarm of bugs or something.

"Yes," Yakov said, staring out the glass with his wife. "What in the world…?"

Another man entered the frame of the video, rapidly speaking in Japanese (about things that might have been another language entirely for all that Byakuya understood) and holding a strange little capsule in his hands. Older Senku nodded, took the capsule, then gestured to the camera. "Want to say hi?" he said in English, his tone a bit teasing. "Chrome, these are the ISS astronauts of June 2019. Everyone, this is Chrome, one of our engineers."

The man waved awkwardly before his gaze locked on something in particular. "Oh, she looks just like Ruri," he said, eyes wide. "I mean, I get why, but the resemblance is just…"

"Yeah, okay, go stand over there," Senku said, giving the man a push. "Don't just stand around mooning over your wife. We've got science to do." When the man left, older Senku held up the little capsule. "This…this is a Medusa."

The bauble slowly lifted up inside the capsule, rotating and shifting impossibly. Again, Byakuya wondered if this was a prank. Desperately, he hoped it was. (He could feel that it wasn't.)

"That cloud is made of devices just like this," Senku continued. "We don't know where they came from. They don't know where they came from. But they can do the impossible." He took a deep breath, then turned. "Ready, Suika?"

"Yes," came a woman's voice.

Senku nodded, then held out his palm and said, "Half meter. One second."

There was a flash of light, and then the older Senku was—covered in stone? What?

A woman with green glasses came into view, a flask in her hand. "The device turns organic material to stone. We think it might be nanotechnology." She poured the contents of the flask over Senku's head. "It's reversible with a mixture of 30 percent nitric acid and 70 percent 96 percent alcohol. Senku said you have a product called nital with the correct ratio, if it turns out you have to fix the world the hard way. Also, if the statues haven't eroded at all, they can be glued back together if they're broken." The stone covering the man on the screen started to glow and then vanished.

Senku shuddered, then sighed and ran a hand over his face.

Byakuya was gripping the console so hard his fingers were turning white. If that's what the devices did… "Is that what happened?" he found himself saying. "I don't understand, but you're Senku from the future, right? Something terrible happened with those Medusa things and now you've used some alien tech to contact the past to try and stop it from happening again?"

Senku chuckled joylessly as he handed off the capsule to the man from earlier. "Ten billion points for you."

The other shuttle members were obviously distressed by this, all of them talking over each other. "It must be a prank," said Shamil, his voice shaking. "A trick. For—for social media or something." Connie was whispering something that might have been a prayer, eyes closed and hands clasped, and Yakov and Darya were back at the telescope speaking in increasingly loud Russian.

Lillian put her hand on Byakuya's shoulder and leaned into the range of the camera. "How can we help?"

Older Senku smiled. "That's going to take some brainstorming." He told them briefly about their original plan, about the year and a half they had wanted to build what was needed. The other astronauts gradually listened in. "What we want to do now is build a communication device, then beam a message at the Medusas in your time from our Medusa. Ours is called Why-man, by the way. You've got limited supplies, so we'll need to figure that out. Little Senku can help from the ground. We can plan and simulate and run calculations over here."

So began a very hectic planning session. Older Senku had given them a timeframe—they needed to have the message sent and received before June 3, 9:00 am Japan Standard Time. The team in the future had apparently been working on this ever since they made contact with Senku a day ago.

ISS ground control in 2019 was confused about all the irregular activity on board. But what were the astronauts supposed to say? The truth was too bizarre.

Lillian's scheduled concert was put on hold. "Technical difficulties," she said in an email. "Everyone is safe and healthy, but there's something wrong with communications. We can fix it, but it will take some time." Yakov sent a similar email to ground control.

Lillian felt a bit useless as all the scientists worked as hard as they ever had. She decided she would be responsible for keeping them all fed and put together some of the easier-to-eat meals, passing out the food and water and nudging them into eating.

Older Senku could be seen talking with all kinds of people coming into whatever space he was using. Languages from all around the world were being used, and the astronauts were surprised to see some of their colleagues and peers among the scientists. Some of them were much older, incongruously so (comparatively out of sync) but it was them. They spared a brief moment for greetings and got back to work. (There would be time to freak out about all of this later.)

It was around 5 pm Japan Standard Time in the future (the future and past were a few hours out of sync with each other) that Senku had some non-scientist visitors.

His face legitimately lit up when he saw whoever had knocked on his door. Byakuya, who'd been following his instructions on making something, was completely forgotten, which left him feeling a bit bemused.

Senku had lost track of time (a feat for him). As yet another knock interrupted his work, he turned, resigning himself to yet another explanation of what Why-man needed to interface with the communications console, and was pleasantly surprised to see Kohaku at the door.

He smiled at her and waved her in, pulling off his reading glasses. "Didn't realize what time it was." She dragged over one of the extra chairs and sat next to him, setting the takeout bag on the desk. He looked behind her. "Where's—?"

"Harassing people."

"Ah. And—?"

"With Ruri. A bit fussy today, didn't want to bug you."

He gave her a look.

She laughed. "Okay, I'll ask her to bring him up." She sent off a quick text while Senku unpacked the ramen noodle bowls and broth cups.

"Oh wow, did you tip the old guy extra today? He put in extra—"

"No, you know how talk gets around. He heard from—"

"Of course he did. Meddling mentalist. How does he—?"

"He just knows people, you know that."

"Everyone, all the time, everywhere? It's freaky—"

"Just because you don't—"

Ruri knocked on the door, holding a grumpy little boy and herding an excitable, slightly older little girl. "Look who I found," she sang gently.

Senku stood up to take the boy, who was reaching for him with grabby hands. "There's my little man," he said, cuddling the sad boy close and smoothing his hair back to feel his forehead. A bit warmer than normal. "I heard you felt sick today. You okay?" The boy sniffled but nodded, burying his little face against Senku's shoulder. Senku then smirked down at the tiny toddler terror currently hugging his leg. "And I heard you've been making friends."

"Helping!" she said back. "I was helping!"

"Hm, I bet you were. Hungry?"

"Yes!" And then she ran over to sit on Kohaku's lap. Senku followed after thanking Ruri for rounding up the kids.

He only remembered he'd been talking to his dad when he saw a very surprised Byakuya and little Senku looking at him from the screen. "Oh," he said, switching to English. "Oh! Hey, kids, do you want to meet someone really cool?"

They nodded.

"Alright. This guy right here is your grandpa Byakuya. My dad."

His daughter launched herself forward to look at the screen better, completely blocking the camera with her face. "Really? The teacher astronaut who told the best stories? Really?" Kohaku pulled her back and held her so she wouldn't block the camera again.

"Granpa," his son said, waving a single hand. "Hi, granpa."

Senku chuckled. "Dad, little me, I'd like you to meet my wife Kohaku and our kids Kei and Okusei."

It looked like Byakuya's call had frozen, but then Senku could see Connie sliding past, working in the background, so Byakuya was apparently still processing.

Little Senku, meanwhile, looked frankly disgusted by the fact that any version of himself had married and had kids.

Kohaku laughed. "Aw, that little baby face. I'd forgotten how cute you were."

Little Senku blushed and sputtered. Senku, meanwhile, reached over and gently tugged a lock of her hair. "What, you don't think I'm cute anymore, lioness?"

She gave him her most deadpan stare. "Nope. Absolutely repulsive. It's a burden to look upon you. I weep for my children's hideous future."

"Mama, Papa is handsome," Kei said in her best know-it-all voice. "You said so two days ago. You said he was handsome and I was pretty and Okusei was cute."

Senku grinned and poked Kohaku's shoulder. "You think I'm handsome? Do you have a crush on me? How embarrassing."

"I'm your wife, you doofus," she said with a laugh.

"What were your names again?" said Byakuya at last, distracting Senku from teasing his wife. "I don't think I heard very well the first time." Senku saw the other astronauts trying to sneak peeks at the screen—they were probably still on speaker, like he'd guessed.

"I'm Kei!" said Kei while raising her hand. "It means gemstone. And beautiful! But mostly gemstone!"

Byakuya smiled. "A good name for a smart, beautiful girl, then."

Kei beamed at her grandpa's apparent wisdom, her dark brown curls bouncing as she nodded. Senku held back a chuckle. Kei then pointed at Okusei. "That's baby Okusei! He's a baby."

"Not a baby," said baby Okusei sullenly. Senku patted his back.

"A big name for a little guy," Byakuya said, raising an eyebrow at Senku. Senku could hear the unspoken, "Really? You named your kid 'hundred million stars'?"

"Just keeping up the family tradition," Senku said with a shrug and a smirk. "With 'hundred nights' for a grandpa and 'thousand skies' for a dad, it seemed only fitting."

"And I'm Kohaku," said his wife. "It's so great to meet you. I've heard so much about you." She didn't say anything about meeting the founder of her village's ancestors, which was probably for the best—no one had actually told the people in 2019 how far away in time they really were.

"A pleasure to meet you as well," said Byakuya, bowing respectfully (as well as one can while in space). Senku was a bit startled by the formality from his normally flippant dad. "All of you. Kei, Okusei, Kohaku."

Senku realized Byakuya wanted to remember them, repeating their names and studying their faces. "Dad, do you know how to take a screenshot?" he asked. There were some computer things that his dad had trouble grasping, which was very funny for an astronaut roboticist and physicist.

Byakuya shrugged. "Sorry, not a clue!"

"Um, I can," said Connie, pushing a bit closer. "If you want." Byakuya floated back from the console to give her space to work.

"Hey, kiddos, we're going to take a picture," Senku said, checking Okusei's face for any of those smudges that just seemed to appear on children. "Can you smile for me, little man? Just for little bit so my old man can have a nice picture of you?"

Okusei hummed and nodded solemnly.

Senku smiled and tapped his nose. "Thanks, Okusei. I appreciate it."

Kohaku held a bouncing Kei steady and Connie said, "Okay, here we go! Smile, everyone!" She presumably took the screenshot, then pulled it up to check it. "It looks perfect, you guys!" She turned to Byakuya. "I can help you send it to your email later, if you want."

He beamed. "Thanks, Connie, that would be great."

Senku, meanwhile, was having a bit of a moment. He dreamed about this sort of thing—of introducing his family to his dad. He remembered crying when he first held Okusei, the little boy so tiny and angry at being evicted from the womb, not just because he was a dad but because he wanted his dad to be there, to hold this new little baby and give Senku a hug (because he would have—his dad loved hugs), to lightly tease him and Kohaku about finally making him a grandpa, anything. And again, finally deciding to adopt Kei after finding her next to the long-broken statues of her birth parents, after taking care of her for a month while half-heartedly looking for a new family for her.

And now here they were, all together in this small way.

He saw Kohaku glance at him, smile, then turn to talk to Byuakuya, reaching over to hold his hand out of view of the camera. They knew each other so well at this point, were so in sync, that Senku honestly couldn't imagine his life without her. They supported each other, helped each other, backed each other up. He knew what she meant with her smile: "Take your time," and her hand-hold: "I love you, you complete dork." He squeezed her hand twice ("thank you, I love you too") and focused on breathing steadily and the warm weight of Okusei cuddled up against him.

His dad was the model he tried to follow as a father. He remembered big smiles and hugs and encouragement to follow his dreams, reprimands and comfort and encouragement to make friends and eat healthy and all the things that Senku tended to forget about when he was in the middle of a project.

I want you to be proud of me, Dad, he found himself thinking. All my life, all of what I do, is because I want to be the kind of man you'd be proud to call a son.

Wow, he really needed some sleep, huh? He huffed as he hid his face against Okusei's hair, instead listening to Kohaku talk about her volunteer work and what the kids were up to.

When his phone buzzed that it was six o'clock, he cleared his throat. "Alright, kiddos, time to go."

Kei whined but eventually said goodbye. Okusei waved sleepily. Kohaku picked up their slightly-less-squirmy-from-tiredness daughter and said goodbye as well.

Senku left the call to Suika and walked out to the car with his family, buckling Okusei into his car seat and turning on the car while Kohaku wrestled Kei into her car seat (she insisted she was big enough to not need one anymore, and when confronted with the reality of her diminutive height, said that she felt taller and that was all that mattered).

Kohaku shut the door with a sigh once their kid was safely restrained, then gave Senku a hug. "Take a nap, okay?" she told him. "Just a little one. Tell everyone I'll beat them up if they bother you."

Senku laughed and hugged her back. "Sounds good. I'll be home sometime tomorrow, for better or worse. Sorry for the messed-up schedule."

"It happens," she said with a shrug. "Life doesn't stop when you have to save the world." She pulled back to look at his face, then smiled softly. "It was great to meet your dad. I'm glad the kids behaved."

He snickered. "He's a dad. He knows what kids are like. But yeah, me too. Little terrors." He had to rub at his eye, sniffing a bit.

She tapped his cheek. "Nap. Seriously. At least a half hour, an hour and a half if you can manage it."

He nodded—human brains needed time to rest. He'd do better work if he was rested, even if it felt like he was slacking off. "I will, I promise. Good luck getting the kids to sleep. Tell them I'll be there to tuck them in tomorrow like normal."

She laughed and kissed his cheek. "We'll need all the luck we can get." Then she was driving off, and Senku made his way back inside.

He stopped by his office to tell Suika and the ISS crew that he'd be resting for an hour and a half, unless they needed him after a half-hour. He also reminded them that they should take breaks, too.

When he woke up from his hour nap (he couldn't sleep longer, too antsy), he came back to his office to see Suika passed out on her desk, head cushioned on her arms. "Go to the break room," he said, nudging her awake. "The cot's free. You'll hurt your neck like that." She mumbled something and trudged her way out of the office.

To his surprise, there was only Shamil visible on the monitor. The cosmonaut saw him and nodded in greeting. "The others are sleeping," he said. "We decided on shifts so someone is always awake."

Senku nodded and got back to work—the world wasn't going to save itself.

At 8:30 am Japan Standard Time, on June 3rd, 2019, the crew of the ISS and the various teams from the future completed the construction of a cross-dimensional communication device that would project a message from Why-man to the Medusas of the past.

Why-man's message was nothing emotionally moving or worthy of epic poems or movies—it was basically a proof of identification and a logical explanation of why the Medusas should move on. Their time could be better spent elsewhere.

And it worked. The humans received no message in response, but the cloud rose away from the moon, disappearing into the darkness of space.

"We…we did it," Senku said, standing in his office with Suika, both of them having been glued to the screen to await the verdict. "We stopped…we…"

He could hear the crews outside his office cheering. He could see the astronauts congratulating each other and the future scientists. Suika hugged him hard, said something with a big smile on her face, and left the office. Little Senku leaned back in his chair with a satisfied smile.

And Senku felt hot tears start to roll down his cheeks. They did it. Past and future, working together to stop a catastrophic event. Little Senku would grow up with his dad. He'd never meet Kohaku or Chrome or any of the villagers—they would never exist—but humanity and all its history would live on, all the good and bad of it, and little Senku would never carry the burden of reinventing everything. He'd probably never meet all the people Senku had met, but billions of other humans would continue to live.

They had only managed to revive 500 million people in the years since Senku had been first unpetrified—so many people were shattered beyond repair, melted in volcanic eruptions, buried in the earth or lost in the ocean, sometimes eroded away until only fragments of them remained. Families were broken and friendships ruined as people were revived out of sync with the people they had known.

Dreams were lost. Lives had been lost. Futures and pasts—so much lost.

Little Senku's life would diverge from here in radical ways—new disasters, new inventions, new problems, new successes. And older Senku was glad. His friendships, as meaningful as they were, and even his family with Kohaku, his two awesome kids, were not worth the destruction of humanity.

He sighed. Most of his life had been dedicated to restoring humanity to any kind of viable civilization and then finding a way to prevent the need for that in the first place. And now he had. Some version of Earth that would have been petrified now would not be. This version of Earth would continue forward.

It was…like a weight was lifted. He'd done it. They'd done it.

He found himself sinking to the floor, his hands pressed to the cool tile. "We did it," he whispered. His tears fell to the tile and he couldn't help the shuddering gasp that shook his whole frame.

Nearly eight billion people saved. They'd never know it, and he hoped they never found out. Let them live, happy and ignorant of what could have torn their world apart.

And now he could focus, without reservation or regret, on the future in front of him. He straightened and wiped his eyes, snickering at himself. When did I get so emotional? I'm getting old.

He could almost see it. His kids, pushing towards and past whatever horizons would be in front of them. His "nephews" and "nieces," free to find themselves in ways their parents had been unable to. His friends, all living their lives as best they could.

"The future is as bright as ever," he said to himself in a quiet voice, the echoes of cheers barely reaching him. He looked out his office window, the rising sun coloring the night sky with the shades of dawn. "Time to get excited."