The next morning arrived—April 30, the final day of the month.
"We're going to conduct health check-ups today," Jin announced after breakfast.
"Health check-ups?" Marikka asked.
"That's right. It's important to monitor your physical condition regularly, after all."
The procedure itself was simple: Lise, the healer automata who had inherited Elsa Randol's skills, would cast Diagnose.
"...I think I'll pass. I'm already at such an age," Eris said, trying to decline.
"It won't take long, and everyone else is doing it," Jin said, gently keeping her in her seat.
Lise stepped forward and began the process.
"Diagnose. Diagnose. Diagnose. Diagnose. Diagnose. Diagnose."
The results for everyone present were available instantly.
"Jin-sama, everything is normal. Marikka-sama, you are also in good health. Rubina-sama, you still have two baby teeth remaining. They will all be replaced by permanent ones soon, so be sure not to neglect your brushing. Greena-sama, there is a slight curve in your spine. Please be careful not to slouch."
Lise reported the findings in order.
"Freddie-sama, your stomach seems to be a bit out of sorts. I will cast Healing on you later."
Finally, she turned to the visibly nervous Eris.
"Eris-sama, you have a heart condition. I diagnose it as an Atrial Septal Defect."
"...!"
An Atrial Septal Defect is a congenital condition where a hole exists in the atrial septum—the wall separating the right and left atria of the heart.
It accounts for roughly six to ten percent of all congenital heart diseases and is twice as common in women as in men.
Because it is a birth defect, standard Healing magic cannot cure it. Such magic works by accelerating the body's natural self-repair mechanisms to their absolute limit, but it cannot fix structural anomalies present from birth.
"Grandmother...!"
Freddie had suspected his grandmother wasn't in the best of health, but hearing the name of the disease made him turn pale.
"Ah, so that is what it is called. Since I was a child, my chest would tighten whenever I moved too much. I've managed to survive this long by getting by with Healing magic, but..."
"Laojun, treatment?"
Without waiting for her to finish, Jin spoke with total certainty.
"Yes, My Lord. We have the medical records left by Elsa-sama. Lise can perform the surgery immediately. It will take approximately one minute and requires no anesthesia. Success rate: 99.99 percent."
"Good. Do it now."
"By your command, My Lord."
"...Wait, what? Surgery!?"
"Eris-san, please lie still for just a moment."
"Y-Yes."
Led by Jin and Reiko, a bewildered Eris lay down on a nearby sofa bed.
"Ready, Laojun? Lise?"
"Yes. Commencing surgery now."
"Preparations complete. Standing by."
Laojun used the Peeping Telescope's Peeper function to look through Eris's chest, visualizing the exact location of the defect.
Sharing that data, Lise readied the Force Rod.
The device was an application of force generator technology. It could penetrate solids, liquids, and gases to perform tasks at a specific target position. This technology allowed for the internal repair of even massive magi-devices like spaceships without the need for disassembly.
Next, Laojun used the transporter to send Magi Bio-material directly into Eris's heart.
Magi Bio-material is the same biological material used to create homunculi. It has the immense benefit of causing no rejection when used in human patients. Once introduced, it quickly fuses with body tissue and is gradually assimilated over time.
It was a medical breakthrough co-developed by Saki, Elsa, and Hanna, with technical support from No. 700672.
Using the Magi Bio-material, Lise repaired the hole in Eris's heart in just five seconds—and it was completely painless.
"It's finished."
"Wait, already?"
Eris was stunned. From her perspective, it hadn't even been thirty seconds.
It was understandable. A disease that had plagued her for her entire life had been wiped away in less than a minute.
Lise continued the treatment.
"Now, I will simply invigorate the weakened heart... Heilverfahren."
A soft light enveloped Eris.
When it faded, Eris looked like a different person. Her complexion was noticeably healthier than it had been just moments ago.
"Oh! The tightness in my chest... it's gone! Jin-san, thank you! Thank you so much!"
"Grandmother! I'm so glad!"
Freddie hugged her, tears of joy in his eyes.
The sight brought smiles to everyone in the room.
＊ ＊ ＊
Later, Jin spoke with Laojun about the origin of the procedure.
"Laojun, I didn't know we had treatment like that available."
"Yes. It is a combined technique developed by Elsa-sama, Hanna-sama, and Saki-sama, with assistance from No. 700672-san."
"I see..."
"The idea of using homunculus biological material to fix structural defects was Elsa-sama's. The concept of performing the surgery via the transporter and the Force Rod came from Hanna-sama. And Saki-sama was responsible for the biological material's adjustment."
"Incredible."
Members of the Jin Family—his wife, his sister figure, and his friend. Jin once again felt a deep sense of gratitude toward his former companions.
"This treatment is impossible without the Peeper, the transporter, the Force Rod, and the Magi Bio-material."
Furthermore, it required the processing power of Laojun and the specialized skills of Lise. In other words, it was a miracle that could only happen on Hourai Island.
"In the past, the World Conference was meant to be notified if a patient required such advanced care."
However, the communication networks had been lost during the Magic Federation Rebellion, Laojun explained.
"Even so, since basic health can be maintained through standard Healing magic, the situation is rarely considered critical."
Laojun added that while some people found the requirement of weekly Healing magic casts a bit tedious, it meant that most people never reached a terminal state.
"Well, that's a mercy at least."
"Yes, My Lord."
As they finished their conversation, Eris and Freddie approached and bowed deeply.
"Jin-san, thank you truly for everything you've done."
"Jin-sama, thank you for saving my grandmother!"
"Don't mention it. We're... relatives, after all."
Jin had almost said "descendants," but looking at Eris, the word felt out of place. "Relatives" was a safer choice.
"...Truly, this Hourai Island is like a land of the gods," Freddie said.
"Oh? You know the origin of the name Hourai?" Jin asked, impressed.
"Yes. I've read the records and books our ancestor left behind."
"I see. Well then, Freddie, let's begin your education."
"...Huh?"
"You want to become a magi-craft expert, don't you?"
"Y-Yes!"
"Then we start with the fundamentals."
Jin led Freddie toward the workshop. Though he hadn't asked the others to come, the whole group followed right behind them anyway.