Magical Girls are the Best Toys

 After having a few hours of fun, Yui with Miyu, after having rested sleeping for a few hours, finally went out of the building into the garden heading for the Magic Tree where Vili continued to eat her infinite tangerines without even paying attention to them and looked uninterested in the whole world focusing only on her snacks which were disappearing at an alarming rate.

"What are you doing?" Yui asked her uncertainty, seeing that Vili is not in a good mood and not wanting to ruin her mood completely. Vili just turned her head, where Miyu could have sworn that she heard the squeak of an unoiled machine and was a little scared when she saw Vili staring at Yui with a visible annoyance.

"Nothing," She said in dead tone and then stood up, eating the last mandarin, then flew up to get in line with Yui's sight, not forgetting to send out an gaze saying 'I'm pissed off' and stared straight into Yui's eyes for a few terribly long moments. "I was just sitting here when you guys set up to see if you could fill this whole closed dimension with your moans forgeting rest of people here. So no, I didn't do anything."

"Well, in that case, it's time to get on with something since we all have time." Yui skillfully ignored the whole atmosphere surrounding Vili as well as her accusing gaze, then changed the subject to something productive that will help them now and will not take up their time unnecessarily, but really Yui just did not want to quarrel with Vili. "Let's deal with the demonic cores, or improve the demons, what do you say?"

Vili sent Yui's dead stare and then simply started to fly towards the suitcases with the demonic cores that were placed next to the building, so they had to go back to it, but that did not bother them. At the same time, Vili signalled to the demons to gather in front of the building, so they had to stop working on the construction.

In general, seventeen demons with tools gathered because they put their weapons away to work on the building, thirteen demons in masks that took bark off the trees, or cut stones into even cubes, or were simply gardeners, six stone bears that repaired things that broke down or did for porters, eight forest wolves whose duties were all related to the trees and three golems that dealt with everything related to the stone.

This surprised Yui, who does not remember creating so many demons, but she quickly remembered one of her conversations with Vila, who told her when she was teaching her attitudes about demons and their formation, that demons in groups are duplicating slowly, the same is true in areas full of mana but faster, also without needing so many demons.

"So if you want to strengthen the demons, then make the commanders for their teams thy be smarter and more efficient in comanding their subordinates". Vili explained to Yui, giving up on her anger, knowing that it would not bring anything and would only waste time unnecessarily after all it was getting quite late.

"So, to practically speed up what happens naturally, right?" Yui remembered again, recalling the lessons she had from Vila on demonology, pointing out that this is like naturally increasing they personal strength, not numbers. Demons multiply then establish their leader, then when they grow even more, more demons evolve and the cycle repeats itself over and over again, which can become a big problem if let alone for too long.

 "Yes, use the demon cores to strengthen them since we have quite a few of them anyway." Vili suggested pointing to suitcases filled with cores, which Yui approached by pulling forty cores out of them, because she thought that the quality of demons is more important from their quantity and chose the first twenty by approaching demons with three pairs of arms.

She used five on two and ten on the one she wanted to be in command. She melted the five cores, which were created from various negative emotions, together and sent this increased crystal inside the demon together with her concept for him, which caused a transformation in him. The lower two pairs of arms merged into one and the upper pair of arms moved to the back of the demon, taking on a more mechanical appearance, where large shields made of amethyst crystal appeared in them, as did the two large swords in his hands.

Grey chivalrous clothes appeared on him with black and amethyst shades on which quickly appeared light armour made of dark amethyst crystal, which was smooth in design. The demon's head did not change much except that the black stone on his face grew larger, creating a black cross with small amethyst crystals that glittered on the two sides of the cross's arms making up the eyes.

Yui did the same with the second demon and then turned to the third demon on which she used ten demon cores. He was very similar to his companions, differing in that the third pair of hands disappeared replaced by flying crystal shields that levitated behind him. He was wearing plate armour and a helmet covering his entire face and only a flash of his eyes was visible.

As Yui was now approaching the demons in masks, Miyuu noticed these crystals, which she linked to the new skill Yui got on her promotion to second rank and she was quite correct in her deduction as Yui now has the ability to create an amethyst crystal which had properties similar to those of an obsidian, while being very prone to enchantment.

When Yui approached the long-armed demons with a masked face, she used five demon cores on two of them. Their hands were shortened to regular length, with long nasty knives in their hands, which looked unearthly sharp with their crystal blades.

Here however the resemblance ends because one became slightly taller getting a black dark green male almost black tail-coat and similarly black trousers and shoes with a similar coloured cloak with a cape and a cylinder lay on his head which now had black shorth hair. He wore white gloves and his mask now took on a more ominous look, where behind it only red eyes could be seen.

The second demon became shorter, gaining long grey hair up to the waist, with a mask that only covered the eyes allowing to see a pale face with red lips that looked like the one on old porcelain dolls. She wore a feminine tail-coat of grey and dark brown and dark grey trousers with black boots under her knees. Her hands were bare showing pale porcelain skin and clean nails. 

Both demons showed amethyst colours and crystals, occasionally emphasizing that these demons belong to Yui and nobody else. Yui herself moved to the forest wolves to continue with her improvements. What attracted more and more attention was Vili, whose mood finally improved when she saw that Yui was finally doing something useful and she would not accept that she finally got through to the next level thanks to that 'physical effort'.

Yui did not improve the wolves, but turned to the dryad that stood in their ranks and it was her who she decided to lead them after using five cores on her which, in her case, made all her stone and rooted parts of her body covered with white fungus with a light shade of green to form a smooth skin that looked human enough but had no flaws.

Her ears lengthened slightly and her head grew an amethyst flower in her hair, which also beautified her amethyst eyes and her face, which now could show human emotions, which the driad showed immediately creating a beautiful smile. Her now naked body was covered by leaves shimmering in autumn colors with twigs and amethyst flowers, which resembled a miniskirt without a back, with a large opening on her belly that went left to the back.

Now, moving on to the stone demons, Yui turned to the golems, where she made one of the five last cores she collected for this task and took on the job of strengthening his core with the cores she had in her hands, and passing her vision on them of new demon form.

The demonic golem now stood two and a half metres tall and wore black-grey stone armour, which had ornaments made of amethyst crystal that pulsated with magical energy. It held a large stone shield with an amethyst cross in it, in his left hand and a large battle hammer in the other, both decorated with amethyst lines also pulsating with energy. Crystal eyes of amethyst colour were shining from inside the stone helmet.

"Are you finished?" Asked curiously Vili, who couldn't hide her smile seeing the powerful demons standing in front of her, wondering what Yui could still do with the remaining crystals to strengthen them.

"No, I was thinking of giving each of the commander an artifacts." Yui said staring at the remaining crystals, thinking what she could do to strengthen them, and she had quite a few ideas coming to her mind, which caused the unconscious smile on her face. Vili, seeing this smile, couldn't wait to see what she was gonna get cooked up this time.

Yui took five demonic cores and approached her knights to use the swords they held to create one powerful two-handed sword for each of them, which were made from a mixture of dark and light amethyst crystal. For the commander, she also reinforced both of his shields, which gave them a black border and a big cross on front.

She gave the crystal watch to the demon in the top hat, who allow him for ten seconds of invisibity until he does not attack and his friend was strengthened  with the dagger that allowed her to teleport a little bit towards direction dagger was pointing at, that power was manifested in the black amethyst dagger, which was of medium length perfectly lying in her hand.

She gave the Golem a medallion which will increase his magical skills in controlling the earth and stones, which will greatly increase his battle power. The medallion itself was set on the Golem's chest in his armour in a place where a normal person's heart would be, and the medallion itself was five centimetres in diameter, completely amethyst with a carved Magic Tree of this garden.

Fenrir and the driad got an artifact that could absorb magical energy from the surroundings similar to the one she used to create the Magic Tree, she gave it only to them because they were the strongest and they are unlikely to die so easily thus losing them, these artifacts will allow them to grow quickly without the need for constant upgrades from Yui.

"I will make the rest of the artifacts for myself and for you Miyu." Yui said just when she finished arming her army, at the end creating them a big piece of amethyst with her skill to make them weapons for the weaker demons just as they did with the stone, this task was given to the Golems, who were to a certain extent able to have effects on it.

"Okay." Miyu answered joyfully rejoicing that she get something from Yui, something that will help her protect her friend and fight together with Yui. 

I have problems with the Internet, so chapters can be published irregularly.