Fifty years passed and no Otsutsuki reared his ugly head, making Rei assume his plan to conceal his planet worked flawlessly.
Funnily enough, both Boruto and Himawari were born to Hinata and Naruto. But these two were their third and fourth child. After being trained by Anko, Hinata knew what she wanted and had the guts to take it. Naruto, the lucky bastard in more ways than one, frequently thanked the Sage for having the Uzumaki stamina.
Honestly, in the end, Naruto didn't become Hokage. Instead, he focused on his family.
His dream of becoming Hokage stayed just that. An unfulfilled dream. Not that Naruto cared overly much. Last Rei heard, he was happy with his life... and his big family.
Sasuke surprisingly married Tenten, and at their wedding, Rei saw why. The girl had a quite pretty face and once she lost the mousy hairstyle, she was fairly beautiful. Plus, her serious attitude undoubtedly appealed to the Uchiha.
Alas, lucky him that he didn't need to recreate the Uchiha clan. The stabby weapon mistress gave him an ultimatum quite early on in their relationship, stating that she would not be used like some breeding sow.
Two kids were her maximum and her words came true.
Then again, knowing that his clan partly survived the 'massacre' seemed to take away a lot of Sasuke's burden so he was fine with Tenten's wishes. They were quite happy together.
As for Sakura... she became Kurenai's, the Sixth Hokage's, apprentice. Becoming an adult made the pinkette calm down and take her kunoichi life seriously. Fast-forward twenty years and the girl became the Seventh Hokage at the ripe age of thirty, serving in the position to this day.
That was one thing even Rei couldn't foretell but it somehow did happen.
Eh, weirder things happened...
During these past fifty years, Rei had his work cut out for him. He thought that finally preventing the Otsutsuki invasion would mean a nice peaceful and quiet life for him but alas, he was totally wrong.
It started slowly, all of his girls getting pregnant... and then the horror began.
Despite being a Master in the Sealing Arts and de facto the secret ruler of the world, Rei had no way to avoid the sleepless nights and the terror of the new parenthood.
Oh, he definitely tried to make his word easier by creating some seals but he quickly understood that freeing Kaguya was easy compared to being a father and taking care of seven newborns at the same time.
The woe was him...
But it didn't end there! Apparently, one child was too little for his girls and every single one of his wives wanted to continue doing her womanly duties. They wanted to have more kids and during these times, Rei fully understood why harems went out of fashion.
He had seen hell...
Unfortunately, he loved them too much to tell them no and he cared too much about every single one of his children to ignore them. So, the next fifty years were very busy and seemed almost unending to Rei.
Complaining aside... it wasn't all bad. Rei was actually happy with his life and the experience of having kids.
As long as it doesn't repeat itself...
Finally, all his wives reached their desired 'quota' of kids, and then Rei instantly put an infertility seal on himself. No matter how much sex he will have in the future, no more kids for him unless he for some ridiculous and completely unrealistic reason decided that he wanted more.
Pfft, as if that would happen.
The most reasonable of his women was surprisingly Mei, only wanting three kids and no more. Her pregnancies were also spread out, having at least seven years in between them so that was quite manageable for Rei too.
Bless her heart.
Mei was not the best mother but she tried her best. Unfortunately, that meant all three of her children got most of her... quirks. As much as Rei tried to subtly prevent it, it was impossible for him since he had other children whereas Mei could be with hers almost nonstop.
Alas, Mei's three kids ended up in the newly created Inter-Space Warfare Research Department, making one weapon of mass destruction after another and having a blast.
Truly... Mei's three little apples didn't fall far from the tree.
Rei was just glad the ninja civilization in these fifty years progressed enough that they could travel to space and other planets, resulting in this part of his family's ability to indulge in their destructive nature without having to damage Rei's planet.
Konan also didn't make much trouble for Rei. Only four pieces in total.
His sweet Konan was always very understanding and wanted only the best for him. Once again, she didn't disappoint and the number of kids she wanted was not something outrageous.
All of her kids possessed the paper release and Rei made sure they knew their fuinjutsu but despite that, three of them ended up as civilians. Rei was saddened but as a good father should, he let them make this choice for themselves.
These three took over the management of the ever-growing Biri-Biri company from Tsunade and their mother and Konan could finally take a permanent break from that function.
Only Rikumi Yotsuba, Konan's second eldest girl, followed Konan's and Rei's footsteps and wanted to become a strong kunoichi like her mom.
Frankly speaking, with how the chakra technology was advancing, being a ninja didn't have many advantages nowadays. Even civilians had at least some chakra with their pathways unlocked. Chakra was a subject even in civilian schools and one didn't need to be a ninja to be a chakra researcher nowadays.
It also didn't help that most didn't have the drive and talent necessary to become a strong ninja and frankly speaking, with the ever-growing destructibility of chakra technology, even chunins didn't amount to much. They were just regular cannon fodder.
Hence, if one wanted to be a strong ninja, S-rank was a must. Of course, reaching this milestone was much more manageable with the training regimen Rei put together with all of his data gathered from Kaguya, but it still required a lot of effort. Most people simply couldn't be bothered.
Rei and Konan made sure Rikumi was put through the wringer when they were sure her desire rang true. Rikumi was forty-two years old right now and she was already the head of one of the Other-sided village's departments while also definitely being in the top ten strongest ninjas worldwide.
Since she wanted to be a kunoichi, Konan nor Rei would not allow her to not reach at least that much.
Plus, Konan probably could see through Rei's plans for the future and knew creating strong people who could defend their home was necessary. After all, they might not be here all the time to protect it if what she had discovered was any indication.
Kaguya had five children with Rei. Yet, her initial desire was two.
She had wanted two boys. But she was given three girls in between her boys, much to Rei's amusement. Even being accused of having a faulty and too feminine seed didn't diminish it.
There was not much to say about her children. They were all ridiculously powerful from the get-go compared to other kids.
Kaguya also wouldn't do the same mistake she did with Hagoromo and Hamura and this time, she took their upbringing firmly into her own hands, resulting in five 'monsters' and the strongest protectors of Rei's little 'empire'.
The girls, Rukia, Remi, and Rina were incredible with sealing arts so much that even Kaguya had a bit of trouble facing them.
The boys, Haruto and Hiroto... the names chosen by Kaguya, ugh... were the usual 'blast it all with irresistible strength' types just like their mother. They went far in their strength development, maybe even farther than Hagoromo and Hamura, but they did not stand a chance against their sisters or Rikumi.
Despite their power, these five were massive mama and papa boys and girls, though. It was really endearing at times.
Pakura and Temari both begot Rei six children over the years, as if competing with each other.
Some went into the civilian sector, some into research, but with their Scorch and Magnet Releases, Temari's kids were godsent for mining resources and that's where most of them ended up, making fortunes for themselves with minimal effort. Especially with the new colonization of other planets. The Magnet Release was incredible for getting new resources from those.
Pakura's kids, on the other hand, were good at glass-making, pooling together, and creating the glass-making division of the Biri-Biri company.
They even started researching different types of chakra-enhanced glass and their findings were what made the colonization of the other planets possible.
Rei liked to spend time with them in their labs since the sealing arts were heavily used in their glass-making but sadly, he didn't do that often. This part of his family was driven and raised to be very self-reliant by their mothers, causing them to focus more on their lives and 'making the family richer and more reputable' rather than the family life itself.
They still attended every family gathering and celebration but... Sigh.
Ringo bore her own seven little swordsmen of the mist, the kids flailing around wooden swords before they could even walk.
With a mother like her, it wasn't any surprise that all seven of them were very good at handling swords but what they really excelled at was forging.
All seven of them. The best forgers in the world.
And Rei couldn't be more proud of this part of his family.
One could think of any high-end chakra technology and it would be made with special alloys developed by Ringo's children. They were the backbone of the quick progress, putting together sealing arts, forging, and masterful Lightning Release to create new and stronger materials at a sufficiently quick pace that the swift development of the technology didn't need to be stopped because of something trivial like insufficient materials.
Without them, nothing of this space colonization era of theirs would have been possible. Not so soon, anyway.
And lastly, Tsunade.
She was hell-bent on recreating the Senju clan.
After Rei flatly rejected her initial quota of hundred kids... duh... they finally found a compromise in the number twelve.
Three girls and nine boys. All good with Wood Release and many of them were in charge of the forestation of new planets, whereas others found their calling in construction or even medicine like their mother.
All were strong ninjas because whether they wanted it or not, Tsunade would not let them be just civilians. Not on her watch. The Senju clan was a ninja clan and that was apparently that.
Despite that, only two were really notable in the ninja circles whereas others were albeit strong... but not reputable for their exploits.
Hana Senju Yotsuba... Rei allowed Tsunade and her kids to retain their Senju names because he knew how much it meant for Tsunade... was the youngest of the girls, yet, the one who took Tsunade's title of the best medic in the world.
Granted, it was mostly because Tsunade no longer made her discoveries public, opting to do research on her new and resurrectable guinea pig called Orochimaru, results of which she could hardly proudly publish.
But it still made both her and Rei proud of Hana and her accomplishments. Hana took over the hospital in the Other-sided Village too after the overjoyed Anko retired because, 'There is finally someone who can take this damned position from my hands!' according to her.
Really, that woman was much better at healing but she still preferred torture rather than what she was good at. No matter how many times Tsunade tried to 'straighten her out', it didn't help.
Hashirama Senju Yotsuba was the other one.
Rei was a bit exasperated at that. It just had to be Hashirama's namesake who stuck out of the fold. The boy was incredible at Wood Style. More so than his siblings. He was yet another of Rei's children who definitely ranked up in the unofficial top ten ninjas worldwide.
But...
Unlike Kaguya's children or Rikumi, Hashirama's passion was not ninja arts but instead... farming.
He was so skilled in his Wood Style that he created a new sub-skill called Plant Style and started farming with it.
According to him, something in the quiet and peaceful life of a farmer was incredibly calming and refreshing.
So... yes. A person like that was in the top ten power ranking. Even his mother, Tsunade, was a tad bit exasperated at how much this boisterous and carefree son of hers acted.
As Rei sat in his rocking chair and looked towards the horizon, he sighed.
He... was bored.
There was simply nothing to do for him.
Or rather, he didn't feel like doing anything anymore.
Only the thoughts of his recent project brightened his mood.
While his little empire was starting with traveling through space, Rei's personal project was something different. He wanted to accomplish inter-dimensional travel.
There was nothing more for him in the Narutoverse and while his Otaku days were a long time over, he still desired to travel throughout other worlds.
Once he finished his inter-dimensional teleportation seal, he intended to take his wives on this new adventure, leaving his world in the hands of his children. Rei never intended to hold onto the power for as long as he could. He accomplished a lot but slowly, he was passing the world on to the future generations. Hence, his boredom.
'Now I only need to find a way to present the idea to my wives. Sage knows Tsunade, in particular, wouldn't like the thought of separating from her children.' Rei grimaced, before wistfully sighing, 'Maybe I should give it another ten years?'
That's what he said ten years ago...
Ah, well, he had all the time in the world.