As Mazumi Mami shared a warm embrace with the three girls in the dormitory, the private research institute owned by the Sakayanagi Family, on the other side of the city, was brightly lit and bustling with activity.
Researchers in white lab coats hurried through the halls, carrying test reports and samples as they moved between departments.
The low hum of the equipment and the occasional sound of someone calling out instructions blended into the distinctive background noise of the night.
It had all started with the bottle of Milky Nutrient Solution Sakayanagi Arisu had brought back from school.
Now, in the innermost core laboratory, a huge pane of one-way glass separated the observation room from the testing room.
Sakayanagi Narumori stood before the glass with his hands clasped behind his back, his eyes fixed on the scene inside the testing room.
Inside, Sakayanagi Arisu had changed into a white patient gown. Her frail frame looked even thinner in the oversized clothes.
She lay calmly on the MRI Scanner's examination table and, at the operator's instruction, was slowly slid into the machine's circular opening.
"Professor Sato, are the other test results ready?"
Sakayanagi Narumori asked without turning around.
Standing behind him was an elderly man with thinning white hair and a gaunt face.
He wore a white lab coat, and the badge on his chest read "Ichiro Sato · Principal Researcher."
He was the most senior and capable researcher at the Sakayanagi Research Institute. Since Sakayanagi Arisu was a child, he had been responsible for monitoring her health and researching treatment plans.
Professor Sato adjusted his reading glasses and opened the tablet in his hands, his voice tinged with mixed emotions. "They're ready, sir."
He paused, as though weighing his words. "After a comprehensive analysis of the chemical composition, spectral testing, and biological activity tests... the conclusion is that, in terms of its material composition, this bottle of nutrient solution is indeed completely ordinary. We found no unusual ingredients or traces of any extraordinary technology."
"Oh?"
Sakayanagi Narumori raised an eyebrow and turned around, a scrutinizing look in his eyes. "You mean... Arisu's improved health is just her imagination?"
"No."
Professor Sato shook his head without hesitation, his tone firming. "The young lady's health has indeed improved. The data clearly confirms it."
He showed Sakayanagi Narumori several charts on the tablet. "Please look here—these are the results of the young lady's blood tests from today, her cardiopulmonary function indicators, and her muscle response speed test... Every result stands in stark contrast to her past records. The changes aren't earth-shattering, but the overall trend is clearly positive."
He looked up, his aged face showing a mix of emotion and shame. "The young lady has undergone countless physical examinations at this institute since she was a child. We know the normal range of fluctuation for every indicator by heart. You could say no one understands her health better than we do."
"And today's data shows that her physical condition is indeed at its best in years."
Professor Sato lowered the tablet, his voice dropping slightly. "We spent so many years and so much manpower and money, yet we couldn't solve a problem that a seemingly ordinary bottle of nutrient solution improved. As so-called 'experts,' we can't help feeling deeply ashamed."
Sakayanagi Narumori was silent for a moment before replying, "You have no need to feel ashamed. This nutrient solution was personally used by the heir to Mizuki Heavy Industries. Given the Mizuki Family's strength and resources, it's hardly surprising if they possess technology far beyond what the public knows."
"I see..." Professor Sato nodded thoughtfully. "If it's technology from the Mizuki Family, then that makes sense. After all, that distinguished family's accomplishments in biotechnology and materials engineering are beyond anything we can hope to match."
However, Sakayanagi Narumori's tone shifted, and his gaze sharpened. "But, Professor Sato—you just said this was an utterly unremarkable bottle of nutrient solution. With your experience and research skills, you haven't found even the slightest clue?"
Professor Sato gave a bitter smile and shook his head frankly. "I'm sorry, sir. The formula for this nutrient solution is completely beyond my understanding. The underlying principles involved may be beyond what current mainstream science can explain."
He paused to think, then offered his theory. "I suspect... its special properties are activated only after it enters the human body. Testing it outside the body can't trigger its true mechanism. In other words, unless we use a human body as a medium, we may never uncover its secrets."
Sakayanagi Narumori was silent for a long while, then slowly nodded. "In that case... all we can do is wait. Once we have more data on Arisu's health, we can see if we find a way through."
Professor Sato bowed. "Understood. I'll keep tracking the changes in the young lady's health indicators."
Some time later, the door to the testing room opened.
Sakayanagi Arisu had changed back into her school uniform and emerged slowly, holding her signature cane.
Her steps were still unsteady, but compared to the weakness that had once made every step seem to drain her of strength, she had clearly improved.
She stopped in front of Sakayanagi Narumori and Professor Sato, tilting her head slightly. "Well, Father, Grandpa Sato—did you get any results?"
Professor Sato exchanged a glance with Sakayanagi Narumori, then lowered his head apologetically. "I'm very sorry, young lady... We conducted a thorough examination, but we still couldn't unravel the mystery of this nutrient solution."
Sakayanagi Arisu was silent for a moment, but she didn't look particularly surprised.
She murmured, "I was somewhat prepared for this... but hearing it in person is still a little disappointing."
Professor Sato looked at the girl he had cared for since childhood, his eyes flashing with a mixture of concern and guilt. "I'm sorry, young lady. I wasn't capable enough..."
"It's all right, Grandpa Sato."
Sakayanagi Arisu looked up and offered a faint smile. "You've already done your best. I'll always remember everything you've done for me over the years."
Her heartfelt understanding and gratitude made Professor Sato's eyes redden slightly.
He bowed deeply. "Thank you for understanding, young lady..."
"All right, Professor Sato."
Sakayanagi Narumori spoke at the right moment, his tone balancing consideration with authority. "Go get some rest. Please redouble your efforts on the research from here on. Even if you can't fully reproduce the original, a copy with similar effects would be enough—keep trying."
"Yes, sir. I'll do everything in my power."
Professor Sato answered solemnly, bowed once more to the father and daughter, then turned and left the room.
The heavy door closed. In the well-insulated room, only Sakayanagi Narumori and his daughter, Sakayanagi Arisu, remained.
After a brief silence, Sakayanagi Narumori broke it first. "It seems the only way to truly resolve your health problems is to ask Young Master Mazumi directly for help."
A knowing smile appeared at the corner of his mouth. "Still... perhaps that's not such a bad thing for you."
Sakayanagi Arisu picked up on the teasing in her father's words and sighed helplessly. "Father... are you in such a hurry to marry me off?"
"Hahahaha—"
Sakayanagi Narumori laughed heartily and waved a hand. "It's not that I don't have that in mind, but more than that, I think this is a chance for you to learn something."
His smile faded, and his expression turned earnest yet gentle. "For example, compromise and understanding."
His tone softened. "I know your nature better than anyone. You're clever, but you're also too headstrong and do as you please. Sometimes, you don't think about the consequences at all. That kind of personality may serve you well when you have overwhelming power on your side, but sooner or later, you'll encounter an obstacle you can't overcome on your own."
He met his daughter's eyes and spoke earnestly. "Now, someone has appeared who can make you 'rein yourself in' a little. That may not be a bad thing."
Sakayanagi Arisu lowered her eyes. After a moment's silence, she nodded gently. "Since you say so, Father... I'll try my best."
"Mm, that's good."
Sakayanagi Narumori nodded in satisfaction and gently patted his daughter's shoulder. "It's getting late. I'll have the driver take you back to school. You have classes tomorrow, so don't miss your rest."
"All right, Father."
Sakayanagi Arisu gripped her cane and turned toward the door.
When she reached it, she suddenly stopped and turned her head slightly. A complicated glint flashed in her purple eyes as she whispered, barely loud enough for herself to hear:
"Try my best...?"
Then she opened the door and walked step by step into the depths of the night, beneath the lights of the corridor.
Behind her, Sakayanagi Narumori watched his daughter's slender figure. His eyes held both affection and a hint of unspoken worry and hope.
A new game of chess had quietly begun.
And the piece named Mazumi Mami was changing its course in a way no one could have anticipated.