Rin placed the jewel in her hand back onto the table in front of them.
"Watch closely. I'll only do this once."
She directed her palm toward the jewel. A flow of mana began to fill the air—subtle, yet extremely controlled.
"And if after this you still think theory doesn't matter…"
Her gaze sharpened slightly.
"That will be your own problem."
Rin began performing her jewel magic, channeling prana into the stone with gentle precision.
Almost simultaneously, Kuro activated his Sharingan.
His eyes turned red, the tomoe slowly spinning, observing every detail of the process—from the flow of prana to the activation of the Magic Circuits occurring as the magecraft was used.
After a few moments, Rin stopped the process and the demonstration was complete.
She then looked at Kuro, immediately noticing the change in his eyes.
"…Those eyes," she said softly.
Kuro didn't appear panicked.
"Just Mystic Eyes," he replied shortly. "It helps me see the flow of prana. Please don't ask further."
Rin was silent for a moment.
Her gaze remained sharp, but she didn't press the question.
Kuro then picked up a jewel from the table.
He closed his eyes.
Focused.
In his mind, he began forming a Switch—a mental image of himself being showered by hundreds of swords.
A pressure.
A threat.
And a drive to endure.
"Resurrección," he murmured as the Activation Spell.
In the next moment, his previously dormant Magic Circuits began to flare, emitting bursts of blue light.
Prana surged violently into the jewel in his hand.
Too violently.
"…Wait—" Rin frowned slightly.
But it was already too late.
The jewel trembled violently before shattering.
The sound of tiny fragments echoed, followed by sparks of energy scattering around.
Kuro reflexively opened his eyes.
His hand was still raised, but the jewel had already shattered.
Silence.
Rin stared at him for a few seconds.
Then she let out a long sigh, massaging her temples.
"…Control," she said flatly, "is more important than power."
Her gaze returned to Kuro.
"You don't lack prana."
Her tone turned slightly more serious.
"What you lack is control."
Kuro looked at the remaining shards of the jewel in his hand.
"…Seems like it," he muttered.
Rin crossed her arms again.
"But for a first attempt…"
She paused for a moment, then looked at Kuro with a hint of interest.
"…Not bad."
Even so, her expression returned to its usual flatness.
"Now clean that up."
She pointed at the table.
"And we'll start over from the beginning."
Kuro followed Rin's instructions without saying much. He quickly cleaned up the remaining shards of the jewel on the table and returned to his original position.
Without wasting any time, he began the magecraft practice again.
The first attempt failed—the flow of prana was still too rough, almost unstable.
The second attempt was better. His control began to take shape, though it was still not efficient.
The third attempt nearly succeeded. The prana structure was correct, only lacking precision at the final stage.
Rin said nothing. She simply stood with her arms crossed, observing every movement of Kuro with the sharp gaze of a teacher.
Time passed.
Finally, the prana flowed into the jewel smoothly, controlled and stable.
The jewel glowed faintly, indicating the charging process had succeeded.
Kuro slowly opened his eyes.
Success.
Rin raised her eyebrows slightly, clearly surprised, though she didn't show it overtly.
"…That was quick," she murmured softly.
She then let out a short sigh before looking at Kuro more seriously.
"Twenty minutes to reach that stage… even for someone with a solid foundation, that's not normal."
Her tone shifted slightly—not just teaching anymore, but observing.
"Don't get me wrong," she continued, "that's not entirely praise."
Her gaze sharpened.
"People who learn too quickly usually miss something. Either long-term efficiency… or true understanding."
She pointed at the jewel in Kuro's hand.
"Do it again. Ten times. If the results are consistent, then I'll consider that you've truly mastered it."
For a moment, Rin fell silent, then added in a lower tone:
"…And this time, I'll be watching more closely."
"Understood," Kuro replied calmly. "Rin-sensei."
The practice continued.
***
Night had fallen over the city of Fuyuki, and the clock struck midnight.
Before he realized it, several hours had passed—and surprisingly, Kuro had mastered everything Rin had taught him.
Now, Kuro walked slowly, his steps calm, while his gaze was fixed on the interface displaying his own status.
Ding!
__________________
Name: Kuro Tokitou (Cain Ainsward)
Race: Human
Title: Reincanator
Job: Magus
***
Strength: 2
Vitality: 2
Agility: 2
Charm: 200
***
Level Circuit Quality: 1
Magic Circuit: 25
OD Capacity: 520
Mana Absorption: 5
__________________
"I didn't expect this," Kuro murmured softly. "Studying the basics of magecraft actually unlocked a system function—Achievements."
He gave a faint smile.
"And the reward granted is 20 Magic Circuits," he continued. "A number that is definitely not insignificant for me."
He raised his hand, activating his Magic Circuits, and at the same time, his Sharingan flared to life—his eyes turning red with a single tomoe spinning for a moment.
He analyzed.
"With the increase in Magic Circuits," he said calmly, "efficiency and output also rise."
After a while, he deactivated both his Sharingan and Magic Circuits.
His hand lowered. His steps paused.
"But… Achievements?" he murmured again. "By the way, what exactly qualifies as an Achievement?"
He furrowed his brow slightly.
"System, can you explain? I forgot to ask because I was too focused on training."
Ding!
[Explanation: Achievement]
[An Achievement is the result of a specific action that meets certain conditions, particularly actions with the potential to alter the course of cause and effect.]
[Each Achievement is evaluated based on its impact on the probabilities of reality.]
[The greater the potential change in cause and effect, the higher the Achievement value granted.]
[Additional note: not all actions will be registered as Achievements. Only actions with a "change value" that meets the system's threshold will be recognized.]
After receiving the notification, Kuro closed it and took a cigarette from the Gate of Babylon, placing it between his lips.
He reached into his pocket, pulled out a lighter, ignited the tip, and drew in a slow drag.
He paused for a moment.
"Hmm…" he murmured softly. "So… it requires specific actions, huh?"
A faint smile appeared on his face.
"At least now I understand."
Suddenly, a reminder interface appeared before him.
Ding!
[System detects that you have not performed your Check-in today.]
[Would you like to Check-in now?]
[Yes / No]
Kuro raised his eyebrows slightly.
"Oh? Already time for the daily login, huh?" he said calmly. "Alright… let's see what I get today."
Without hesitation, he selected "Yes" on the interface.
Ding!
[Congratulations, you have received 5 Catalyst Gacha Tickets]
Five white tickets with star patterns appeared before him, and Kuro immediately picked them up.
His eyebrows furrowed.
"Gacha tickets again?" he murmured. "But catalyst version? What does that mean, System?"
Ding!
[Providing explanation...]
[Catalyst Gacha Tickets are special items distinct from standard Gacha Item Tickets.]
[Standard Gacha Item Tickets produce objects or resources randomly with low specifications.]
[Catalyst Gacha Tickets produce catalysts, which are mediums used to summon specific existences.]
[A catalyst is an object, concept, or residue of an existence that has an attachment to the target summon.]
[The specification level of a catalyst affects the accuracy of the summoning result.]
[The higher the catalyst specification, the higher the probability of obtaining the corresponding existence.]
While reading the notification, Kuro slowly took a drag from his cigarette, then pulled it from between his lips.
He exhaled gently. White smoke drifted and slowly vanished, blending into the night air.
"So… these are some kind of special tickets, huh?"
He smiled faintly.
"Now I'm curious… what catalysts did I get."
After saying that, Kuro crouched down.
If before he had used the tickets one by one, this time he used them all at once.
The five tickets in his right hand shattered into particles of light, and the next moment, five items appeared on the asphalt in front of him.
Ding!
[Congratulations, you have obtained a lock of Xu Fu's hair, which can be used as a summoning catalyst for Xu Fu.]
[Congratulations, you have obtained a Bottle of Reason, which can be used as a summoning catalyst for Astolfo.]
[Congratulations, you have obtained a Round Table Fragment, which can be used as a summoning catalyst to summon one of the Knights of the Round Table at random.]
[Congratulations, you have obtained a Tiamat Horn Fragment, which can be used as a summoning catalyst for Tiamat.]
[Congratulations, you have obtained a lock of Osakabehime's hair, which can be used as a summoning catalyst for Osakabehime.]
Kuro stared at the five items without moving immediately.
"The results… aren't bad."
He paused for a moment, before a thought crossed his mind.
"Though… this lock of Xu Fu's hair and Osakabehime's hair makes me think about exploiting the Caster and Assassin classes in this War."
Moments later, he stored everything in the Gate of Babylon.
Of course, he wouldn't use them now, as there were still other things he needed to handle first.