A/N: A friend from the RWBY Wiki Chat, known as PrimeXam created this idea, and the dots just connected from there. Please enjoy the story.
The sounds of a sleeping Youkai could be heard from inside the Hakurei Shrine, as a small team of beings occupied the stairs to rest slightly, the young evening moonlight shining upon them.
Sitting on the bottom step organizing her toolkits, was a certain Kappa, known as Nitori Kawashiro. With bright blue hair tied into twintails and inquisitive azure eyes, Nitori currently sat deep in thought at the recent events. Her attire consisted of a blue dress with dozens of large scale pockets around the hem of the skirt and her upper arm, while a dark aquamarine backpack rested upon her shoulders. A golden key on a strap could be seen in front of her, hung on a necklace. Additionally, the Kappa also wore a grass green hat with a white wispy symbol on it, deep blue wellington boots and also carried a cattail with her. Tools of all sorts and types could be seen sticking out from her pockets, but hundreds more were laid out on the ground, each one being packed away. Ranging from mechanical toolkits to workshop machines, the Kappa was extremely well equipped for all manner of situations requiring an engineer's expertise.
Beside her, also adjusting her own supply of medical equipment, was a doctor, known as Eirin Yagokoro. Dark grey eyes filled with curiosity and thoughtfulness, and long silver hair could be seen on her face, while a large braid was on her back. A type of doctor's uniform was worn by the skilled professional, with its front and back covered with constellation patterns, while trigrams in the style of Yin Yang Orbs lined the bottom hem. A modified nurse's cap could be seen upon her head as well. A bow crafted of the finest Lunarian materials and arrows tipped with incredible power rested upon her back, currently on standby.
Slightly higher on the steps, resided another four figures, each emitting power unlike any in Gensokyo.
The first had long swept back pure white hair and a short beard of the same color, his features stern yet kind. His attire consisted of green and white themed hakama as well as an overcoat to match. Known as Youki Konpaku, he was a half phantom half human gardener for Hakugyokurou. Two blades forged in top quality materials rested upon his back, ready to be drawn as a moment's notice.
The second had purple hair, as well as a modified Shrine maiden's uniform which snuggled around her form comfortably. Her features were kind and pleasant, even as a frown adorned her face at the moment. Known as Mizuki Hakurei, she was the Hakurei Shrine Maiden responsible for the Shrine.
The third was known as Yuyuko Saigyouji, her short pink hair bundled up into a bright blue mob cap, where on the front was a hitaikakushi with a red ghost insignia and a veil of cool blue behind her head. A light blue and white kimono with a dark blue trim and white designs wrapped around her form, while dark shoes with blue ribbons attached to them rested on her feet.
The fourth and final member, was known as Yukari Yakumo. Long blonde hair was coiled upwards into her red ribbon adorned mob cap as dark golden eyes were clouded with contemplation and thought. She wore a purple Chinese-style tabard with various Trigrams over a pale pink Western-style dress. A pink parasol also remained held within her left hand.
As the six unique people sat in contemplation, the silence broken only by the packing of Eirin and Nitori, the latter asked in a shy, tentative voice, "Um... Is this really for the best..? To morph someone so far into the realm of machinery..."
Eirin added in, "I've also performed the most extensive operation upon the Youkai's entire genetic and biological structure. I question whether it was for the best, to delve so far into the unknown."
As the other four turn to face Yukari and Yuyuko, the question as to whether it was a good idea clear in their eyes, Yukari sighed as she responded, "It is indeed for the best. While Gensokyo is still being formed, contact with the Outer World must be maintained, otherwise we risk hostile forces breaching the barrier over time. Just as the Barrier will soon protect us, we will be unable to learn of what is occurring from the outside. For that, someone must be able to manipulate the Barrier entrances with ease, much like you, Mizuki."
With a nod, Mizuki commented, "It is true. Just as I will soon be responsible for maintaining the Barrier and solving Incidents that occur from within, they will be my counterpart, the one to solve the Outer World Incidents in order to protect Gensokyo."
Yuyuko added in, "I hope the training and enhancements we've made will them..."
Youki patted Yuyuko on the shoulder, saying warmly, "I'm sure the child will be fine. After all, they have our blessings, our training, and has already lived for three hundred years-"
The party of six fall silent suddenly, reminded of the Youkai's past upon their explanation.
Eirin murmured, "Three hundred years of constantly being the hunter and hunted, advancing through the most advanced techniques that both Youkai and humankind could teach them, regardless of the field. With experience in so many fields, that Youkai is the perfect soldier, the perfect Operative in terms of capability... Especially with all our modifications..."
"I'll be deploying tomorrow, Mom." A voice came from within the Shrine.
The six whirled around at the voice, shocked by what they saw.
A massive, 8 foot tall armor clad figure, stylized in a terrifying figure from hell itself, themed in black met their eyes. Two blades were sheathed upon their back, both Odachis, tempered by the finest smiths of both Youkai and human blacksmiths, while a massive backpack attached to the back could be seen filled to the brim with various materials, ranging from cooking pans to weapons, to even clothing and many other such items of interest.
With a bow to Yukari, the figure awaits their answer from the person that they owed their life to.
With a soft smile, Yukari walked over to the figure, and patted them on the head, whispering, "Look at you, all grown up. It still feels like yesterday that I found you, nearly dead among an entire battalion of the finest Youkai troops sent to kill me all those years ago. When I took you in, and you became the closest thing to a family for me. Time flies by so fast, and I just wanted to say," Yukari hugs the figure around the chest, as the armored being wraps their arms around her in a comforting hug, she whispers, "Be safe. And come back alive for me, okay dear?"
A soft voice resounds from the angled helmet of demonic proportions, "I promise mom. I'll never forget you all..."
As the touching moment ends, and the du untangle themselves from one another, Yuyuko says with cheer in her voice, "Well, since this is your last time here for a while, let's throw a party!"
As various words of acknowledgment meet the suggestion, Mizuki sighs as she walks back into the Shrine saying, "I'll get the food and drinks ready."
Yukari and the figure both join Reimu, as Yukari says, "We'll help you."
As the conglomeration split up into various tasks, the moon was still young in the night sky, as the preparations were finished quickly, and the festivities began in earnest.
As the full moon almost reached its peak on the turn of 1885, the team of six see off the seventh member off with a farewell.
As hugs are exchanged and words are exchanged, Yukari stands before the person who became her family, her pride and joy.
As the two share one final hug, the figure goes to stand in the secondary magic circle next to Mizuki Hakurei, as the Youkai of Boundaries and the Hakurei Shrine maiden concentrate their powers, even as the tail end of a dragon can be seen flying above, disappearing into the clouds as it released a small wave of power down to the magic circles, landing in the center. The incantations complete and the Dragon God's blessing and full power given, the creation of the Great Hakurei Barrier, the very barrier that would separate the newly named Gensokyo from the rest of the world begun its cycle.
At the same time, the figure floated into the air, as the spell took effect on them as well, the power of the Barrier infusing itself within them as well.
As the Barrier was about to reach the critical point of completion, the figure looked down at Yukari, and gave a small sign with their hands in the shape of a heart. Yukari returned the gesture, grinning proudly as she watched her family disappear into the Outer World.
The barrier complete, Yukari whispered, "Good luck, daughter..."