The morning in Ash Lane burned cold. Gray mist clung to the ground, swirling with faint traces of ether dust that shimmered like dying stars. Jiro stood in the open courtyard behind Rein's underground hideout — shirtless, trembling slightly as the frigid wind cut across his skin.
Rein stood a few meters away, his mechanical arm glinting faintly in the rising sun.
"Training starts now," he said. "If you want your body to endure a core, it must first learn pain — and respect it."
He tossed a metal band toward Jiro. The boy caught it — a heavy iron ring.
"Put that around your waist. It weighs fifty kilos."
Jiro blinked. "F–Fifty!?"
"Don't talk. Move."
Rein pointed toward the cracked outer streets of the district. "You'll run ten laps around Ash Lane's perimeter — roughly six kilometers each loop. Don't stop. If you do, double it."
Jiro groaned, strapping on the weight. "You're insane…"
Rein's lips twitched. "No. I'm preparing you to survive your own power."
---
By the second lap, Jiro's breath burned. His legs screamed with each step as he darted past abandoned cars and rusted signposts half-buried in ash. The once-bustling district now lay in ruin — silent buildings, shattered billboards, the ghosts of a forgotten city.
The watch on his wrist pulsed faintly, tracking his vitals. Heart rate: 180. Energy flow unstable.
He gritted his teeth. "Shut up… I'm not done yet!"
Each time he slowed, Rein's voice echoed through the communicator.
"Don't waste air on complaints. Focus on rhythm — breath, step, pulse. That rhythm becomes your core's heartbeat."
---
When Jiro finally stumbled back into the courtyard hours later, the sun was bleeding red across the horizon. He collapsed to his knees, panting hard, ash coating his sweat-soaked skin.
Rein didn't even look impressed.
"Not bad for a first run," he said flatly. "Next — pushups. Two hundred. Then iron grips until your hands tremble."
"Y–You're serious?"
Rein crouched beside him, eyes like cold steel. "When your body breaks, it rebuilds stronger. The core will only bond with a vessel that has learned endurance."
Jiro said nothing — just gritted his teeth and started. His arms shook violently by the time he reached fifty, and blood ran faintly from his knuckles where the rough ground tore his skin.
Rein watched silently, arms folded. The faint hum from his mechanical limb was the only sound besides Jiro's ragged breathing.
When Jiro collapsed after his last pushup, Rein threw him a flask of blue fluid. "Drink."
Jiro took a swig, feeling heat spread instantly through his chest. "What is this?"
"Condensed Essentia. It repairs micro-tears in muscle and nerves. Pain fades, but exhaustion teaches discipline."
---
By nightfall, Rein stood before a glowing pillar in the middle of the courtyard. It pulsed faintly, feeding energy into the surrounding area.
"Now," he said, "sit."
Jiro obeyed, dropping into a cross-legged position. His whole body ached.
Rein drew three circles in the ash with his metal finger — one near Jiro's head, one over his chest, one around his abdomen.
"These represent the core sites: Aetherion in the mind, Essentia in the heart, Vitanova in the lower soul channel. You've already reached Inner Flame, which means your core is stirring."
He looked down at Jiro. "But for you to become a Meridian Walker, you must fill every nerve and channel in your body with the energy that aligns with you — the one you sensed during Inner Flame."
"Energy that aligns…" Jiro murmured. "You mean… from Ether Beasts?"
Rein nodded. "Yes. Their essence, or meditation if you're skilled enough. Either path leads to resonance. But both demand control."
Jiro hesitated, eyes lowering. "I… already have a core."
Rein's brows furrowed. "Explain."
"In the cavern… during the trial." Jiro's hand instinctively touched his stomach. "There was an egg — a beast core, I think. It fused with me. Left a mark right here."
He lifted his shirt slightly. The faint blue sigil pulsed in the dim light, its veins spreading outward like roots.
Rein knelt beside him, his mechanical hand scanning the mark. The readout flickered violently — [Core Signature: Unknown Origin].
His expression darkened. "This… isn't just a beast core. It's symbiotic. It's feeding energy through you."
"I thought it was broken," Jiro said quietly. "But every time I meditate, I can feel it… moving."
"Then focus," Rein said. "Let's see what it does."
---
The air grew still.
Jiro closed his eyes, steadying his breath. He recalled Rein's earlier words — rhythm, pulse, breath. Slowly, he sank into stillness.
At first, nothing happened.
Then — a spark.
The mark on his stomach began to glow, faint at first, then brighter. Thin streams of blue light crawled from it, spreading along his skin like veins of living energy. His body tensed as the glow deepened, threads of light weaving into his bones.
Rein's eyes widened. The scanner on his wrist went wild.
"That flow— impossible. It's channeling energy into your dermal layer and skeletal marrow…"
Jiro gasped, feeling warmth spread through him — not painful, but immense. The light traveled downward, spiraling toward his lower spine.
"It's… moving on its own," he said between breaths. "It's like it's… feeding."
"Don't fight it," Rein warned. "Just observe."
The blue glow thickened, a faint hum rising in the air. Jiro's breathing synced with it unconsciously — every inhale drawing in faint particles of ash, which turned into shimmering light before sinking into his skin.
Rein could sense it — the energy wasn't entering Jiro's body, it was being claimed by it.
The sigil pulsed once, twice… then dimmed.
Jiro exhaled, collapsing forward, drenched in sweat.
Rein approached slowly, scanning again. "Your mark absorbed external Ether like a living core — but instead of storing it, it distributed it to your skin and bones. Then some of it… went deeper. Toward your Vitanova region."
"So… what does that mean?" Jiro asked weakly.
Rein looked at him for a long moment. "It means you're not cultivating energy, Tensai. The energy is cultivating you."
Jiro froze.
"That mark is changing your body's structure — rebuilding you into something that can host more than one core. If it continues, you'll either ascend far beyond the human limit… or your body will collapse trying."
The night wind howled faintly, scattering the ash between them.
Jiro looked down at the still-faintly glowing mark, his heartbeat echoing in his ears.
"I don't care," he said softly. "If it means getting strong enough to find him… I'll take the risk."
Rein's gaze softened, then hardened again. "Then rest, Meridian Walker. Tomorrow, we begin the real training — the kind that breaks gods."
He turned and walked toward the shadows of the ruined district.
Jiro sat in silence, hand pressed to his stomach, feeling the faint hum of something alive beneath his skin — ancient, waiting.
"What are you…?" he whispered to the mark.
It pulsed once in answer, like a heartbeat beneath the earth.
And above the ashen sky, lightning flickered faintly — blue and white.
*****