Rei stood surrounded by his wives in his 'laboratory' located in his mansion in the Village on the Other Side. All around them were papers with sealing arrays haphazardly strewn all over the place, only the middle of the room contained a very complicated seal drawn onto the floor.
Today was the day his long years of research will finally bear the fruits of his labor.
"You have finally finished 'it', huh?" Konan hummed, a bit miffed.
She didn't like the fact Rei was again in his research mode for the past few years. The last time he entered it, he made the artificial bijuu. Sure, that brought a lot of joy to their lives and provided them with completely loyal companions that enhanced their strengths to an unimaginable degree but the process of creating them was extremely dangerous. Konan still didn't forget Rei admitting he almost blew himself up while making the necessary seals for the creation of their bijuu.
So when one pleasant morning after a lovely night of merrymaking Rei told her he had a new important project... her sluggish and pleased mood instantly evaporated. Konan only barely managed to bite her lower lip in order to prevent herself from screaming her throat sore at Rei.
Yet, Konan knew she couldn't stop him. As much as she wanted to, she knew his 'important research projects', as he called them, were really important for their future. Whenever Rei called a project important, it meant it would either raise their strength significantly or be a preventive measure against something bad from happening.
That still didn't make these 'important projects' any safer though. Konan could only hope Rei would be responsible enough to not actually emulate Mei and destroy himself alongside the planet because of some minor mishap.
'Really, sometimes I feel as if I was surrounded by kindergarteners.' Konan bitterly thought.
Rei looked at Konan, reading her inner turmoil from her almost indifferent expression, and wisely kept quiet without answering her rhetorical question. He was well aware of her attitude to his practical approach when it came to testing his seals. Then again, he did have Shadow clones. Ah, women. Why couldn't they understand that experiencing blowing yourself up was totally different than actually blowing yourself up?
"Anyway," Rei turned towards Mei, "you look quite excited!" He exclaimed.
Pakura, Tsunade, Konan, and Ringo were all busy so it was Mei who was helping Rei the most during this project. He still kept many things about it a secret but Mei, under all that guise of childishness, was incredibly smart. Rei had no doubt she came to her own conclusions about the goals of his project.
"Yes! We spent years on this and now it is finally finished!" Mei bounced up and down and for some reason, Rei had a hard time tearing his gaze from her vibrant auburn hair moving up and down with her momentum and clashing with her wide green eyes full of excitement.
It was only when Tsunade put her hand on the top of Mei's head while grinning widely did Rei finally snap out of his reverie.
"Look at her." Tsunade teasingly drawled, causing Mei's smile to stiffen, "So excited that you are finally done, Rei. Yet, I wonder why she is hiding that deep sadness she is fee..." A glint flashed through Tsunade's eyes but Mei quickly turned around and put her hand on Tsunade's mouth, desperately silencing her with a pleading look.
Tsunade's grin only widened when she saw an understanding glance from Konan and a raise of an eyebrow from Pakura. Ringo... just glared at the back of Mei's head but that was a common thing between the two redheads.
As for Rei... he had five overly caring women. He got good at hiding things he didn't want them to worry about and discovering things they were hiding from him. After years of their relationship, that was bound to happen eventually.
Even without the Senjutsu-powered emotional sensing which was becoming a kind of a passive sixth sense in Tsunade's case due to her uninterrupted continuous use of the Senjutsu Mode... And yes, that made it basically impossible to lie to her... Rei knew why Mei was sad and why he was hiding it.
Since she was his assistant, for the most part, they spent a lot of time together in his laboratory, doing things... things that not always could be connected to his research or seals.
Rei was just glad his laboratory was soundproof and actually had a bed. Mei could be really wild and willful when she wanted.
It was obvious Mei knew that now the research was over, her convenient excuse to spend time with Rei was also gone. Rei, on the other hand, knew his girls more than even they thought. Heck, he practically raised Mei and saw every step of the development of her mindset.
It was so obvious she didn't care about the seals at all. She was passable in the craft... but she couldn't care less. Sure, the final result probably did excite her but honestly? Rei knew she 'sacrificed' her free time and became his assistant in order to spend more time with him, rather than due to wanting to actually help him.
What Rei didn't say was that the research could be done a year ago if Mei didn't join. That girl knew how to play his buttons far too well, distracting him from work...
And when Yugito and Yagura finally married two years ago and announced Yugito with a child... in the following weeks, Rei didn't manage to do much seal work as he was deeply focused on exploring Mei.
Fortunately, Rei's ability to control natural energy and absorb it into his body made him able to make himself fertile and infertile on command. He was not gonna bring a kid into a world when there was still the threat of the Otsutsuki clan hanging above their heads. Nu-uh.
Rei also knew it was just one of Mei's whimsical moods. After a few weeks, she couldn't even look Rei into the eyes for a few days from shame. Deep in her heart, she didn't really want a child. She only liked the idea of that happening. Once her brain kicked in, however, Mei quickly realized she was not ready yet.
"Just start it." Ringo sighed, tiredly rubbing her eyes. "I still have work in my forge."
"Ha! I bet you are so cranky because you thought he was calling you to do something more enjoyable than showing off the results of his research!" Mei butted in with a sneer.
Ringo clicked her tongue at Mei in irritation, "Whatever. At least this way your bragging about all the time you get to spend with him will finally end, you nympho."
"What was that, you weapon pervert!?"
A pressure suddenly enveloped the room, pressing on both Mei and Ringo, weighing them down while completely bypassing the other occupants. Now that made both girls quiet down and turn towards Rei in embarrassment as if they were little kids that were just scolded.
Since the artificial bijuu finally matured, Rei and his wives gained a lot of 'perks'. One of which was the heaviness of their chakra which in turn enhanced their 'intent'. Not unlike the release of killing intent, Rei released his irritation with a full weight of his chakra behind it at the two bickering women.
It was harmless... against them. Their bodies were enhanced to an incredible degree when fully-matured bijuu settled in them. The weight of Rei's chakra made them only slightly hunch over unlike the air around them that was cracking from the pressure.
"I am starting." Rei decided to cut the chase, unwilling to give Mei and Ringo another chance to start arguing. "You all have the two seals I gave you earlier on you?"
After a round of agreement, no matter if it was enthusiastic, grumbling, or muttering one, Rei sighed and kneeled on one knee, putting his hands on the edge of the seal in the middle of the room.
Before his girls could even blink, the world shifted around them, becoming...
All five women turned their heads in bewilderment as they looked around and could only think, 'What the hell?'
Rei just smirked, spreading out his arms, "Welcome to the outpost hidden on the Other Side... of the Moon."