In a magnificent mansion owned by the noble Rokutou family, a child was born on a night filled with joy. A warm and emotional atmosphere enveloped the entire mansion as the baby's first cry echoed through the halls, marking his arrival into the world.
A doctor walked forward slowly, carrying the newborn in his arms, and approached a man standing nearby with a face full of emotion—a mixture of relief, happiness, and deep emotion. His first child had been born safely.
The doctor gently handed the baby to him. The man received the child with utmost care, as if even the slightest touch might disturb the miracle cradled in his arms. He gazed at the tiny face and smiled, overwhelmed by a happiness that words could not fully express.
"Have you prepared a name for him, sir?" the doctor asked softly.
The man nodded slowly.
"His name is Sei. With our family name, he will be known as Rokutou Sei," he answered with a proud smile.
Several years passed.
Little Sei was now four years old. He could freely walk anywhere he wished within the vast mansion. However, unlike other children his age, Sei had no interest in playing or running around the garden.
His favorite places were the family library and his father's study. His father was a high-ranking government official, and it was there that Sei spent most of his time.
That day, Sei once again sat quietly in the library, absorbed in thick books, reading from morning until night without showing the slightest desire to play.
From a distance, his father watched the scene with a mix of amazement and confusion.
His wife approached him and asked gently,
"You look uneasy. What's wrong, my dear?"
The man let out a quiet sigh, his eyes still fixed on Sei.
"It's just… Sei is different from other children. He doesn't like to play. He prefers spending his time with books."
His wife smiled softly.
"Isn't that a good thing?"
"I know," he replied quietly. "But it feels strange. At the age of two, he could already understand people's personalities. At three, he spoke clearly and could read picture books on his own."
She placed her hand on his shoulder, comforting him.
"Don't worry too much. Sei isn't strange. He's simply developing faster than other children."
The man fell silent, once again gazing at his son—a small child with eyes far too deep for his age.
One day, the Rokutou mansion welcomed a special guest—a longtime acquaintance of Sei's father. The man came from the Middle East and was widely known across many nations.
His name was Aqlan Ibn Nuraym, a genius revered as a master of magical theory as well as arcane science.
That afternoon, Sei's father was having a relaxed conversation with Aqlan in the family's living room. Their discussion was warm, filled with light talk that occasionally turned serious. Before long, Sei appeared at the doorway, having been asked by his mother to greet his father's guest.
With slow, slightly reluctant steps, Sei approached. He did not speak right away, instead fixing his gaze on Aqlan with intense focus—a look more befitting an observer analyzing a subject than a child his age.
Aqlan immediately noticed the gaze.
In fluent Japanese, he asked gently,
"What is your name?"
Sei looked straight into the man's eyes before answering calmly,
"My name is Rokutou Sei."
"I see. Sei… that's a good name," Aqlan said with a smile.
"Thank you," Sei replied briefly.
Aqlan then took a toy out of his pocket.
"Do you like toys? I brought this from my homeland. Would you like to try it?"
Sei glanced at the object briefly. There was no interest in his eyes. After a few seconds, he spoke flatly,
"I can make it myself."
Aqlan was slightly taken aback. This was the first time he had ever met a child who showed no interest in toys—let alone one who confidently claimed he could make one himself.
"You can make toys?" Aqlan asked, intrigued.
"Yes," Sei answered. "With paper, I can make an airplane. With wood, I can make a doll. If I add springs, the doll can move as well… though only to a limited extent."
The explanation came out so naturally, as if it were common knowledge. Aqlan looked at the small child with undisguised admiration.
"You possess an extraordinary amount of knowledge for someone your age," he said. "How about I give you a gift… a new book?"
"A new book?!"
Sei's eyes immediately sparkled with excitement—far more enthusiastic than he had been upon seeing the toy.
"I'll send you books of science and knowledge from my homeland. You may read them," Aqlan said warmly.
"Alright!" Sei answered without hesitation. "I'll be waiting for them."
Without delay, Aqlan contacted his colleagues back home and arranged for all the promised books to be sent.
Three days later, dozens of books were neatly lined up in the Rokutou family library.
The moment he saw them, Sei could not hide his excitement. He immediately picked up the books and began reading without pause. He started with basic mathematics, then progressed to intermediate levels, and eventually challenged himself with advanced mathematics.
For an entire day, Sei immersed himself in studying and memorizing complex formulas, engraving them one by one into his sharp memory.
That evening, Aqlan observed him from a distance, witnessing a level of dedication utterly unnatural for a child of his age. The next day, his curiosity drove him to create a written test. He wanted to know just how far the abilities of the child named Sei truly extended.
That morning, a hundred mathematics problems lay on Sei's desk—ranging from basic to intermediate and difficult levels.
Without the slightest hesitation, Sei began solving them. Even his calm demeanor alone was enough to shock Aqlan.
Before long, Sei put down his pencil. Aqlan approached and asked,
"What do you think of the problems, Sei?"
"I think… they're quite difficult," Sei replied while reviewing his answers to ensure nothing had been missed.
"Let me check."
Aqlan took the answer sheet—and for the countless time that day, he was stunned. Out of one hundred questions, eighty were answered correctly.
"You got eighty out of a hundred correct," Aqlan said quietly.
Sei lifted his head.
"Which ones are wrong? Please teach me."
The request made Aqlan smile faintly. He began explaining the mistakes, and with a single explanation, Sei immediately understood—as if the difficult concepts had merely been waiting for the right moment to click.
Thirty minutes passed.
"I'm sorry, Sei," Aqlan finally said. "I need to discuss work matters with your father. For now, study on your own, alright?"
"Okay," Sei replied with a small smile.
Aqlan left the library and headed to another room within the mansion.
After finishing his mathematics studies, Sei's interest shifted to another book. His eyes stopped on a title unlike the others:
Fundamental Knowledge and Understanding of Magic
He began reading it seriously.
The book explained that the history of magic began with the Second Bearer of Revelation. His name was not recorded, but the methods and theories he left behind were described in detail. It also explained that every human is born with mana or aura, each possessing a different capacity.
These differences could be influenced by heredity.
If both parents possessed large mana capacities, their child would also have a large capacity. If the father's capacity was large and the mother's small, the child would tend to have a large capacity. However, if the father's capacity was small and the mother's large, the child would most likely inherit a small mana capacity.
After reading that section, an idea began to form in Sei's mind.
He wanted to measure his parents' mana capacities—of course, secretly, without their knowledge.
To do that, he needed a tool called a Mana Indexer.
However, such a device was only owned by official guilds in each city—organizations responsible for managing dangerous work such as exploring ruins and dungeons.
In this world, dungeons or ruins appeared in areas with extremely high concentrations of mana. These places were usually abandoned, poorly maintained, and rarely approached by humans. Dungeons were classified into various ranks, from D- to A+, depending on their level of danger.
Sei thought for a moment.
Bringing his parents to a guild would be far too suspicious.
Finally, a bold decision took shape in his mind.
He would create a Mana Indexer himself.