The formula was wrong.
It wasn't catastrophically wrong—not the kind of structural failure that would scatter raw mana across the garden and startle Kairi through the soul thread. It was wrong in the way a word is mispronounced by someone who has only ever seen it in a book. It was functional, almost correct, but it lacked the "breath" of reality. It was missing the vital essence that only becomes obvious when you stop looking at the map and start looking at the terrain.
Riku had been holding the mana sphere for eleven minutes.
The training garden was his alone this afternoon. Late autumn 1989 had stripped the maple trees at the garden's edge to bare, skeletal branches. The light coming through the overcast sky was flat and pale, the kind of illumination that made the edges of the stone lanterns look sharper than usual. Hiroshi was away in the city on business he hadn't explained, and Yuki was inside with Kairi, working on early mana-sensing exercises that Riku wasn't yet permitted to observe.
The garden existed in a specific, heavy quiet.
He rotated the sphere slowly between his palms. The asymmetry was in the eastern node, a tiny hiccup in the flow that pulsed on every breath like a stone in a shoe. He had identified the flaw three minutes into the session, and he had spent the eight minutes since then deliberately not fixing it.
That was the exercise. Yuki's instructions from two weeks ago sat behind his eyes like a second awareness: Anyone can build something clean. A master can hold something broken and keep it from shattering.
He held it. He watched the eastern node vibrate with instability, threatening to cascade and collapse the entire structure, and he forced his will into the gaps to shore it up.
The system hadn't assigned a quest for this session. Sometimes, the interface went quiet, leaving him in a room it hadn't provided the key for. He had come to prefer these moments. There was something honest about progress that existed simply because he willed it, not because a blue bar was filling up.
"Your left anchor is drifting."
Riku didn't jump. He hadn't heard her approach—he hadn't been meant to—but he felt the temperature of the air change as she stepped into his space.
"I know," he said, his voice strained with the effort of containment.
"How long?"
"Since the beginning."
Yuki moved to his left. She didn't interfere with the field, but her presence was a weight of its own. She was wearing a heavy winter kimono, the scent of cedar and dried tea clinging to her. He could feel her attention the way one feels the weather shifting before a storm.
"Why haven't you corrected it?"
"Collapsing and rebuilding is easy," Riku said, his eyes tracking a spark of mana as it whirled through the eastern node. "Holding something imperfect without letting the imperfection spread... that's the actual problem. It's the difference between a perfect theory and a messy reality."
A long silence followed. Yuki circled to his right. He tracked her in his periphery without breaking his focus on the sphere.
"Third stabilization formula," she commanded. "Recite it."
He did. The words were clean and automatic, the mathematical underpinning running parallel to the maintenance of the sphere. Two months ago, this multi-tasking would have required a deliberate, exhausting split of his consciousness. Now, it was just true.
"The variant. Faster."
He shifted mid-recitation. The sphere flickered—a single frame of instability—and he caught it before the light could die.
"Again."
This was Yuki's method: compression. She stacked demands until something either broke or adapted. Riku had learned early that breaking was temporary and adapting was permanent, so he had stopped experiencing the two as different things.
Faster. Again. Hold the eastern node. Recite the variant. Don't let the asymmetry spread.
"Stop."
He stopped. The sphere held, humming with a frantic, uneven energy.
"Close your eyes."
He obeyed. Without visual reference, the field became a landscape of pure sensation—pressure, warmth, and the faint electrical "stinging" of active mana. The eastern node was a jagged peak in an otherwise smooth plain.
"The formula," Yuki said, her voice dropping to a whisper. "Don't recite it. Forget the words."
He waited, his brow furrowed.
"Show me," she said.
For three seconds, Riku didn't understand. Then, the realization hit him with the force of a physical blow. He had been treating the formula like a set of instructions—a recipe. But the formula wasn't the recipe; it was the description of a truth.
He stopped trying to remember the notation. He reached past the words entirely and looked at the mathematical structure underneath—the fundamental geometry of how energy interacted with space.
The eastern node stopped drifting.
It didn't happen because he corrected it. It happened because he finally understood why it was drifting. The understanding itself reorganized the field. The asymmetry didn't disappear; it resolved, the way a musical tension resolves into a chord.
All eight nodes settled into a perfect, crystalline alignment. The sphere didn't just look stable; it felt true. The difference between a sentence that was grammatically correct and one that actually meant something.
[NEW SKILL ACQUIRED]
Formula Visualization Lv1
Perceive the mathematical structure underlying magical constructs. Identify inefficiencies and optimization points through direct intuition.
XP Bonus: +180
The sphere hung in front of him, perfectly balanced. He opened his eyes and saw the world differently—he could see the faint geometric "lines" where the sphere met the air.
Yuki was watching him with an expression he couldn't quite name. It was somewhere between recognition and satisfaction, as if she were noting the exact second a season changed from autumn to winter.
"Again," she said softly. "From the beginning. Structure, not form."
He let the sphere dissolve. He built it again. It took eleven seconds to reach stability, and this time, the eastern node settled on its own. The understanding had already integrated into his soul.
They worked until the light failed and the 1989 neon of the distant city began to glow against the clouds. Forty constructions later, the effort had vanished. It was no longer a translation of a foreign language; he was speaking the original tongue.
"Enough," Yuki finally called.
He let the final sphere dissolve and sat in the grey dusk. The garden was still. From inside the house, he heard Kairi—a tuneless, distracted singing that meant she was happy.
The soul thread hummed: Content. Warm. Curious.
"You modified the exercise again," Yuki said, looking at the bare maple tree.
"Yes."
"You've been doing that consistently." She turned to him, her eyes dark in the fading light. "Your father does the same thing. He takes what he is given and builds past it before anyone tells him to. It makes you difficult to teach, Riku."
"I know. I'm sorry."
"I didn't say it was a problem." She tilted her head. "It means you will outgrow every framework we build for you. Which means we must keep building better ones. You moved the schedule forward today."
--DxD--
Inside, Kairi had stopped her singing. She was sitting in the kitchen doorway, her small face carry the serious expression she got when she was paying attention to things she didn't fully understand.
The moment Riku stepped through the door, she pointed at him. Her small finger was entirely solemn. Through the soul thread came a feeling rather than words—a sensation of shifting, of something becoming larger.
He crouched to her level. "Training. Something clicked."
She held the point for another moment, her gaze too sharp for a one-year-old. Then she dropped her arm and sent a pulse through the thread: Bigger. Good.
[LEVEL UP]
Level 9 → Level 10
[QUEST COMPLETED]
Sharpen the Edge — Reach Level 10
[QUEST ASSIGNED]
Sharpen the Edge — Reach Level 15
Current: Lv 10 — 0/800 XP
[STATUS]
Name: Riku Snow
Age: 6 years
Level: 10 (0/800 XP)
HP: 121/121
MP: 158/158
STA: 134/134
STR: 22 | DEX: 29 | CON: 21 | INT: 30 | WIS: 32
SP: 0/0 (Sealed — Level 25 required)
[SKILLS ACTIVE]
Gamer's Mind Lv2
Gamer's Body Lv2
Beginner Swordsmanship Lv5
Mana Control Lv4
Footwork Fundamentals Lv4
Observation Lv2
Breath Synchronization Lv2
Mana Awareness Lv3
Energy Masking Lv2
Formula Visualization Lv1 (NEW)
[ACTIVE QUESTS]
Sharpen the Edge — Reach Level 15
Soul Thread — Maintain the connection (Stable — strengthening)
He stayed crouched at Kairi's level a moment longer than necessary. Something had shifted today. It wasn't just a level; it was a door swinging fully open. The room on the other side was far larger than the gap had suggested.
"Come on," he said, patting her head. "Let's eat."
She stood and walked into the kitchen without further comment. She was her mother's daughter, through and through.
Riku followed her. Behind him, the garden went dark, the skeletal trees waiting for the snows of 1990 to arrive.