"『Völlig Genesen』"
"...Ngh."
"Jin-nii, are you okay?"
"Yeah, I'm managing. I think the pain is starting to fade."
At the Mansion on Hourai Island, Elsa was casting healing magic on Jin.
It was September 29th. Twelve days had passed since Jin had returned home after settling the unrest among the demon race.
During that time, Jin had been receiving healing magic once every day.
Initially, Reiko had been the one casting it.
Midway through the process, after Elsa examined how well his body was integrating, the task of casting the healing magic was handed over to her.
This change occurred because Jin's other treatment—the cure for Elsa's Mana Overload Syndrome—had resulted in a successful Genesung.
＊ ＊ ＊
The story goes back eight days.
"Jin, how do you plan to prepare water with only one-millionth of a gram dissolved in it?"
"I'm quite curious myself."
It had been quite an event when Jin explained to the gathered Jin Family that he had found a way to cure Elsa's Mana Overload Syndrome.
"Jin-sama! I-Is it true...? Can Elsa's illness really be cured!?"
Her biological mother, Mine, had clung to him with teary eyes.
"Jin! You're amazing! To think you found a cure for Mana Overload Syndrome, a disease considered incurable in this world!"
Reinhard was incredibly excited.
"A 'mental catalyst,' you say? To think such a substance existed...!"
Toa was impressed, his eyes showing a hint of academic hunger for the material.
"How on earth are you going to weigh out one-millionth of a gram!"
Saki pushed forward, demanding an explanation.
In any case, the rest of the group was just as stirred up, and the room was in an uproar.
"Jin-nii... will I really... be cured?"
Elsa alone remained quiet, her eyes welling up with tears in a way that left a lasting impression on Jin.
Saki and Toa were watching with intense curiosity to see how Jin intended to create an aqueous solution with one-millionth of a gram dissolved in 100 cc of water.
"Is it even possible to weigh out something that small?"
Saki watched with interest, wondering if Jin's Craft Magic possessed that degree of precision.
"No, that's impossible even for me. But if it's 0.1 grams, I can weigh it using this."
As he spoke, Jin showed Saki and Toa the device he had just finished.
"What is this? It's a strange shape."
It was a top-loading balance.
In this world, scales were typically hanging beam balances or steelyards; this was the first top-loading balance Jin had ever created.
"It's easier to weigh things this way."
Hanging balances had the disadvantage of strings being attached to three points on the pan, which made it difficult to place or remove weights and samples. In contrast, the top-loading balance was far more efficient to work with.
Jin intended to give this new type of top-loading balance to Saki once he finished this particular task.
"You can measure 0.1 grams, but that's one-tenth of a gram, right? How are you going to get to one-millionth..."
As Saki continued to tilt her head in confusion, Jin gave her a hint.
"The mental catalyst dissolves in water, but its properties don't change. If you evaporate the water, it precipitates back into its original form."
"Hmm?...Wait. No way, Jin!?"
Seeing Jin prepare water in a massive container, Saki finally realized the answer.
"Yeah. If I want one-millionth of a gram in 100 cc, I just need to dissolve 0.1 grams in 10,000 liters, right?"
In other words, if he dissolved 0.1 grams in 10 tons of water, he would have an aqueous solution of the required concentration.
Jin, who had collected water in what was less a container and more a small pool, added 0.1 grams of the mental catalyst and used 'Homogenize' to create a uniform solution.
"From this... let's see, I'll set aside one liter."
Thinking he might encounter others who needed it besides Elsa, Jin prepared a little extra of the precious medicine.
He divided it into ten 100 cc crystal medicine bottles, then proceeded to separate the mental catalyst from the remaining solution.
"『Extraction』"
"Ohh."
Saki let out a voice of admiration.
After extracting the nearly 0.1 grams of mental catalyst from the massive volume of water, Jin carefully sealed it and discarded the excess water.
"Now, let's have Elsa drink this."
Holding the bottle, Jin started toward Elsa but stopped. Elsa was already standing right in front of him.
"...Elsa."
"Jin-nii."
Elsa stared at the bottle in Jin's hand.
"Is that... the medicine?" she asked.
Jin nodded and held out the bottle.
"It is. There shouldn't be any harmful components mixed in. You can examine it if you'd like."
However, taking the medicine, Elsa shook her head.
"No. This is medicine Jin-nii made for me. I will... take it."
With that, she downed the liquid in a single breath.
"...It doesn't taste like anything."
"Well, I suppose not. 0.1 grams in 10 tons of water. Not at a concentration of one part per million."
"Jin, is Elsa cured now?"
Saki, who was watching nearby, asked with interest.
"No, it seems it takes about two days for the mental catalyst to be absorbed by the body and finally settle into the brain cells."
"Hmm, I see."
＊ ＊ ＊
And so, we return to the present.
Two days after taking the medicine, Elsa had experienced an unusually refreshing awakening.
"...Is this proof that the medicine worked?"
Of course, it wasn't as if she had been a poor sleeper before, nor had she been feeling unwell.
It was the sensation that a certain "offness"—something so constant she hadn't even recognized it as a problem—had vanished.
It was as if she had once believed a score of 100 was perfection, only to realize there was a level beyond it.
Or perhaps it was like the clear feeling after a cold's nasal congestion finally clears up. At any rate, she felt wonderful.
When she told her mother, Mine, the woman wept with joy and pulled Elsa into a tight embrace.
"Elsa... Oh, thank God..."
Ever since it was discovered that Elsa had Mana Overload Syndrome, Mine had always stayed by her side, acting as an outlet for the excess mana.
Excess mana usually manifested in the form of a fever.
Whenever Mine felt that Elsa had a slight fever, she would immediately have Elsa use magic to vent the energy.
By the time she turned thirteen, Elsa had learned the sensation herself and was able to handle it on her own. After Jin created the bracelet that absorbed excess mana, she no longer had to do even that, and she had thought she could live as a normal magi. She had savored the happiness of having a normal body.
But this time, it went even further.
"Jin-nii... my benefactor."
The person who had rescued her from the Unifilar after she had abandoned her home.
The person who had given her a place to belong as a sister figure when she was lonely.
The person who had saved her biological mother and allowed them to meet.
The person who had created the bracelet to resolve her Mana Overload Syndrome.
The person who had taught her the new world of magi craft.
The person who had shown her the path to higher heights through the science of another world.
And now.
The person who had completely cured the Mana Overload Syndrome she thought she would have to live with for the rest of her life...
"...I will dedicate my everything to repay this debt."
Having secretly made that resolution, Elsa heard that the supplemented cells composing Jin's body were inactive. She had volunteered to perform the treatment herself to resolve it.
"『Diagnose』... They've been activated quite a bit."
＊ ＊ ＊
When Elsa had first examined Jin's body in earnest, she had been surprised by its imbalance. But now...
"More than half have been activated."
Hearing that, Reiko, who had handed over the role of casting the healing magic to Elsa, also smiled.
"In less than ten more days, Jin-nii's body will be complete."