The Squad 12 Department of Research and Development laboratory sat in the northwest corner of the Seireitei.

The entire Squad 12 barracks had always felt different from any other division. Corridors stacked with half-finished spirit tool components. Walls bristling with monitoring probes and cables. The air carrying some smell that was never quite identifiable — disinfectant, maybe, or machine lubricant, or both. The Spiritual Wave Measurement Research Division's lab took up the entire second floor, nearly half the building's footprint. All four walls were embedded with display screens scrolling real-time Reishi concentration data from Soul Society and the World of the Living.

Hiyori Sarugaki stood at the main control console, hands on her hips, brow locked into a scowl.

She was Squad 12's lieutenant and the head of the Research and Development lab. Blonde hair in two spiky tails, freckles across her nose, short enough that most people didn't notice her until she was already yelling. A foul temper was her defining trait. Nobody in Squad 12 went near her when she was in a bad mood.

Right now, her mood was very bad.

"What the hell is this data!" She slammed a palm on the console hard enough to rattle the screens. "A Reiatsu fluctuation frequency this strange — is it a Hollow or Kidō? Baldy!"

Her eyes fixed on a specific dataset.

It was the Reishi monitoring record transmitted back from the World of the Living three days ago, the complete Reiatsu data from the Squad 13 investigation team's mission site, covering the special Hollow that Yoruichi Shihōin had killed. The volume was massive. From the moment the squad entered the underground pipes to the moment Yoruichi left the scene, every Reishi fluctuation had been captured by the Research Division's monitoring network, precise down to the millisecond.

She had already reviewed it three times. This was the fourth.

"Interesting," she said through her teeth. When Hiyori said "interesting," it meant she had found something that made her furious.

She pulled up three waveforms and overlaid them. The first was the Reiatsu fluctuation of the core Hollow beginning to stir when the shell Hollows' Reiatsu circuit was severed. The second was an extremely faint signal coming from the direction of the pipeline, frequency almost too low to register, barely distinguishable from the ambient Reishi noise. The third was the Reiatsu shift curve during the core Hollow's actual awakening.

Three waveforms, stacked on top of each other. Hiyori's pupils shrank.

"You've got to be kidding me..." Her voice dropped. "Baldy! Someone's playing dirty!"

The peaks and troughs of the second and third waveforms aligned almost perfectly. Not similar. Aligned. Every fluctuation in that faint external Reiatsu signal corresponded precisely to a critical point in the core Hollow's awakening sequence.

Hiyori stared at the screen. Her hands slowly closed into fists.

After the shell was destroyed, someone had used that Reiatsu to wake the core. And whoever did it knew this Hollow's Reiatsu structure inside out, knew the core's awakening mechanism, knew exactly what frequency was needed to trigger it, knew the precise window in which to intervene. They hadn't been attacking the Hollow. They had been operating it.

"The Reiatsu circuits of the three shells were precisely calculated. The core's awakening mechanism was deliberately built in. This isn't just a Hollow — it's a constructed piece of work." Her voice stayed low. "Mimicry-parasitic type. The shell conceals the core while the Reiatsu circuit handles both functions — shielding and sustaining. When the shell is destroyed, the energy released by the circuit's collapse serves as the core's awakening signal. But on top of that, an external activation mechanism was installed as a failsafe. Even if the collapse energy wasn't enough to awaken the core on its own, an external operator could manually complete the activation. Double insurance."

A beat of silence. Then she drove her fist into the console.

"How could something like this form naturally! Baldy!"

Someone had created this Hollow. And that someone was inside the Seireitei.

Hiyori wiped the three waveforms from the screen and brought up the external Reiatsu signal in isolation. The Research Division's data was precise down to the millisecond, precise to the rise and fall of every Reishi fluctuation. But Reishi didn't leave names behind. Once the activation was complete, that Reiatsu had bled back into the ambient noise and was gone.

She stared at the waveform for a long time.

Then she thought of the Kidō teacher from Shin'ō Academy. Seijūrō Kidōin.

She'd met him once, when Kirio Hikifune had gone to the Academy to give a lecture. She had no patience for that kind of bookish academic type, but she couldn't deny it, the man genuinely understood Kidō structure. Not because of how much he'd memorized. Because of how he thought. He didn't treat Kidō as a tool. He treated it as a phenomenon, something to be taken apart and examined.

And on that mission to the World of the Living, it had been Kidōin who first identified the abnormal structure of that Hollow. It had been his three Bakudō barriers that severed the shell's Reiatsu circuit.

His call had been right. If no one had interfered, the core Hollow should have kept sleeping after the shell was destroyed, lying dormant until the Reiatsu circuit fully dissipated. He never should have encountered it. That young squad member named Aoki never should have died.

But he had encountered it. And Aoki was dead.

Someone had awakened the core. And it had worked.

Hiyori archived the data and set the encryption permissions. Then she turned and walked out of the lab, her footsteps hitting the floor like she was trying to break something. She was going to find Kirio Hikifune.

Kirio Hikifune was drinking tea in the Squad 12 captain's office.

She wore her captain's haori, purple hair pinned into a traditional updo, swirl markings on both cheeks, black lipstick. Full-figured and warm in the way that made people forget she ran one of the most technically advanced divisions in the Seireitei. When Hiyori shoved the door open, Hikifune was in the middle of a sip.

"Little Hiyori." She lowered the cup. "What's wrong? You look terrible."

Hiyori dropped the data terminal on the desk. "Read it yourself."

Hikifune picked up the terminal and read through it. Then read through it again.

The smile didn't leave her face. But the warmth behind it did.

"Someone created that Hollow." Her voice was calm. "Mimicry-parasitic type, double-insurance awakening mechanism. Shell conceals the core, external activation as a backup. Nothing this precise forms on its own."

Hiyori's fists were tight. "Kidōin's judgment was right. After the shell was destroyed, the core should have stayed dormant. If no one had tampered with it, Aoki wouldn't have died."

Hikifune was quiet for a moment.

"Classify this as internal Squad 12 confidential," she said. "No one accesses it without my authorization."

Hiyori didn't ask why. Her temper ran hot, but she'd worked beside Hikifune long enough to know when to stay quiet.

Hikifune picked up her teacup. Set it back down without drinking.

Whoever had built that Hollow understood Kidō and Reiatsu structures at a level that surpassed nearly every researcher in Soul Society. And that person was somewhere inside the Seireitei.

That evening, Hikifune went to the Squad 5 barracks.

Shinji Hirako was in his captain's chair with his feet on the desk, flipping through a fashion magazine from the World of the Living, something about pairing a bob cut with a flat cap. When Hikifune walked in, he dropped his feet to the floor. His expression didn't change.

"Yo, Miss Hikifune. What brings you all the way out here?"

Hikifune sat across from him. No preamble.

"You've heard about Squad 13's mission in the World of the Living three days ago."

Shinji's easy smile dimmed. "I heard. Seijūrō Kidōin was with the squad. They ran into a special Hollow. A young member was killed."

"Hiyori analyzed the Reishi monitoring data from the scene," Hikifune said. "That Hollow wasn't natural. Someone created it. Mimicry-parasitic type, double-insurance awakening mechanism."

Shinji's brow tightened slightly.

"The three shell Hollows formed a Reiatsu circuit that kept the core dormant. When the shell was destroyed, the collapse energy should have served as the awakening signal for the core. But someone installed an additional external activation mechanism on top of that. Even if the collapse energy wasn't sufficient, external interference could manually complete the activation." Hikifune's voice stayed even. "Double insurance."

Shinji was quiet for a long time.

"You're saying someone built this Hollow, and then that night, personally triggered it."

"Yes."

"To what end?"

Hikifune looked at him. "I don't know. But Seijūrō Kidōin's judgment was correct. If no one had interfered, the core never would have woken up."

Shinji didn't say anything.

He thought about that afternoon on the stone-paved path at Shin'ō Academy, the look on Kidōin's face when he'd said, there's a very clever student. He thought about Sōsuke Aizen's first solo mission, and the unexplained quarter-hour gap in the mission report. He thought about every flawless performance Aizen had turned in over the past six years.

He'd never had evidence. Not once. But what Hikifune had just said was like a needle finding a nerve, driving straight into the thought he'd been stepping around for six years.

Someone had created that Hollow. Someone had personally activated it. Someone whose understanding of Kidō and Reiatsu structures surpassed nearly every researcher in Soul Society.

And Sōsuke Aizen was the cleverest student Seijūrō Kidōin had ever taught.

Shinji leaned back in his chair. He didn't say the name. Hikifune didn't ask for it.

Some things didn't need to be said out loud.

➤ Next: Encountering Yoruichi Again

Chapter 12 - Encountering Yoruichi Again

It was on an ordinary afternoon that Seijūrō saw Shinji Hirako again.

He had been invited by Squad 5 to conduct a Kidō instructional session. The invitation had been signed by Shinji himself, phrased casually in his usual style. Seijūrō walked the stone thoroughfare of the Seireitei, and the outline of Squad 5's barracks emerged in the afternoon light, solemn and quiet, exactly as he remembered.

Shinji Hirako was waiting at the entrance.

Pale blond hime-cut hair falling past his shoulders. Hands tucked into his sleeves. That inscrutable smile on his face. His appearance hadn't changed at all. When he spotted Seijūrō, he grinned, the tongue stud catching the sunlight.

"Yo, Sensei Kidōin. Long time no see."

Seijūrō nodded. The two of them didn't have much history, a few joint missions, a few chance encounters. Shinji would occasionally drop by the Academy to ask if there were any promising candidates that year, and Seijūrō would answer honestly. They maintained a polite, collegial distance, neither close nor cold.

Shinji led him inside. They passed through hallways, crossed courtyards, and moved past the Squad 5 members going about their business. A figure approached from the other end of a corridor, not particularly tall, shaved head, wearing a Squad 5 Shihakushō.

Shinji waved a hand without looking back. "Sōsuke, go handle the afternoon squad duties."

The man bowed slightly. "Yes, Captain Hirako." His voice was flat.

Seijūrō's gaze settled on him.

Shaved head. Narrow eyes. A high nose bridge and a face like it had been cut from stone. A completely unfamiliar face.

Shinji glanced back at Seijūrō.

"Come to think of it, he was your student. You've had a lot of them, I know — but he wouldn't be where he is today without your recommendation~"

Seijūrō paused.

One of my students? He'd taught class after class, but he remembered every single one. Maybe Captain Hirako had it mixed up.

Had Shinji just called him Aizen? Maybe it was a habit, calling a temporary fill-in by the previous person's name. That happened in the squads sometimes. You got used to a name, and it slipped out even after the face changed.

The bald man gave him a slight nod, then turned and walked away, steps even, posture straight. Seijūrō watched him disappear at the end of the corridor and didn't think about it further.

When the Kidō session ended, Seijūrō left the Squad 5 barracks.

He didn't head back to the Shin'ō Academy right away. Instead he walked the stone roads of the Seireitei for a stretch. Afternoon sunlight sifted through the gaps in the canopy overhead, scattering broken patches of light across the blue-gray flagstones. He crossed the main road and passed into a grove he didn't usually frequent. The trees here were older and taller than the ones in the Academy's courtyards, their canopies closing out the sky until the light went dim as dusk.

Then he saw someone.

She was sitting on a horizontal branch of an old pine, posture so relaxed it was almost insolent, one leg bent with her foot planted on the bough, the other hanging loose, a bare foot swaying idly in the air. In the afternoon light, that foot drew the eye: a clean arch to the instep, long toes with neatly trimmed nails. A strip of brown skin showed at the ankle, and above it, black under-tights traced the line of her calf up into the shadows of the pine boughs.

She wore all black, a sleeveless, close-fitting top made of fabric so thin it followed every curve of her brown skin. The sides were cut open wide from the armpit down, leaving her ribs bare and the faint line of her side visible. Sunlight came through the leaves in pieces, falling across her bare shoulders and collarbones. Her brown skin caught it and held it, a faint warm sheen like a coat of thin gold. Her lower half was wrapped in equally fitted black trousers, tracing the clean line from thigh to calf.

Short purple hair, cropped level with her ears, sharp and clean. A few loose strands across her forehead had been blown casually aside, leaving her brow open and her eyes fully visible, and her eyes were impossible to look away from. Gold pupils, like two pieces of amber soaked in sunlight, startlingly bright inside all that shadow. Her gaze came down from the branch and settled on Seijūrō with a languid, unhurried appraisal. Like a leopard stretched across a tree limb, sizing up someone who'd wandered into its territory.

Her features had an unadorned sharpness to them. High brow bones. A straight nose. A jawline clean as a blade's edge. Her lips were full, tilted up at the corners into something that wasn't quite a smile. In her right hand she held a skewer of dango, popping them into her mouth one at a time. Three were left, each coated in golden-brown glaze that caught the light in a greasy shine.

Yoruichi Shihōin.

Seijūrō stopped.

"Yo." Her voice was easy, the tail end of the word drifting upward like it had been hummed through her nose. "Kidō teacher from the Shin'ō Academy."

Seijūrō gave a slight bow. "Lady Yoruichi."

"Drop the 'Lady.'" Yoruichi dropped from the branch. She landed in front of him without a sound, bare feet settling into the pine needles like a leaf finding the ground. She was a little shorter than him, but standing there, her presence filled the whole grove. Up close, those golden eyes held a glint of quiet amusement, like two amber beads with light shining through them. And her skin, up close, was even smoother, not the pale of someone cloistered indoors, but the deep, alive color of someone the sun had claimed.

"We met once before. In the World of the Living."

"Yes."

Yoruichi looked him over. Her gaze moved from his face to his shoulders, then from his shoulders down to his hands. Those gold eyes didn't pretend to be doing anything else. She was evaluating him, and she didn't bother to hide it.

"Back then your Reiatsu was completely spent. You couldn't even cast a first-level Hadō." She paused. "How about now?"

Seijūrō was quiet for a moment. "Better than before."

Yoruichi smiled. Not a polite one, a frank smile with appreciation behind it. When she smiled, those gold eyes and brows curved into something genuinely attractive, the sharpness softening into an openness that made it easy to relax around her.

"Reading the structure of an unusual Hollow under pressure, setting up three Bakudō barriers at the same time, and your instincts held up too — you thought to use Seki to block a killing strike." She extended the dango skewer toward him. "Want one? Brought them back from the World of the Living."

Seijūrō looked at the skewer and took it.

Yoruichi leaned back against the pine tree, arms crossed, ankles crossed. Her bare feet rested on the dark pine needles, her toes curled slightly, nails catching the light in small flickers. She kept watching him.

"Your read on that Hollow was right. The outer shell concealed the true body, and the Reiatsu circuit was doing double duty — cover and sustenance at the same time. You identified its structure the moment you saw it." Her tone sharpened a little, though the curve at her mouth stayed. "If the Executive Militia had that kind of judgment, I'd sleep better at night."

Seijūrō bit into a dango. Cloyingly sweet.

"Kirio Hikifune is interested in you," Yoruichi said. "So is Hiyori. That Squad 12 crowd doesn't take notice of many people."

Seijūrō looked at her. "What about you, Lady Yoruichi?"

Yoruichi tilted her head. Her short purple hair swept across her ear. She seemed briefly surprised by the directness of the question. Then she smiled, wider this time, showing a row of even white teeth. The branch shadows and scattered light reflected in those gold eyes, all at once like a mirror and like a window.

"You're different from most Shinigami I've met. Most of them only care about how strong their Reiatsu is, or how sharp their Zanpakutō is. You don't. But you're not one of those lazy, useless types either." She held his gaze. "Yeah. I'm interested in you too."

She pushed off the pine tree and clapped him on the shoulder. The force behind it was considerably more than Shunsui Kyōraku's hand had been, back when. Her hand was warm and strong. Through the brown skin, the faint outline of muscle was visible, not the hand of someone raised in comfort, but one shaped by years of gripping, climbing, and fighting.

"Come by Squad 2 sometime when you're free," she said. "The Onmitsukidō training grounds are a lot better than that gravel patch behind your Academy."

She turned and walked away. Brisk steps. Short purple hair swaying at her ears. The black top clung to the flow of her back muscles, shoulder blades shifting faintly beneath the cloth. Her bare feet moved across the pine needles and gravel without hesitation, each step light, each step sure. A few pine needles caught on the black under-tights at her ankles and shook loose as she went. After a few paces, she raised one hand without looking back, wrist turning to expose a stretch of brown forearm, the gesture easy and familiar, like waving goodbye to someone she'd known for years.

Seijūrō stood there holding the half-eaten skewer of dango.

"What was that... That last expression was practically like a cat's..."

Then he realized something.

What Yoruichi had said — the Onmitsukidō training grounds are a lot better than that gravel patch behind your Academy — meant she knew. That he went to the mountain behind the Academy every day after class to train, alone.

Yoruichi Shihōin. Captain of Squad 2 of the Gotei 13. Commander-in-Chief of the Onmitsukidō. The Flash Goddess. She had been watching him in secret. More than once. And he hadn't noticed a single time.

The wind moved through the grove. Pine needles hissed softly overhead. He looked down at the skewer in his hand. The bamboo still held the warmth of her fingertips. He finished the last dango, turned around, and walked back toward the Shin'ō Academy.

Behind him, on Yoruichi's side of the grove, a figure stepped out from behind a pine tree without a sound.

She was small, standing beside Yoruichi she would only come up to her shoulder. Straight-banged black hair cut clean and level with her ears, framing a face with young, sharp features. Pale gray eyes. Not the gold-amber warmth of Yoruichi's, something colder, like winter mist, a gaze still and cutting, the kind that caught every small thing and let none of it go.

She wore standard Onmitsukidō dress, the upper Shihakushō halter-necked and open at the back, leaving her slender shoulder blades and the back of her neck bare, while black sleeves ran from her wrists up past her elbows, fitted tight to the lines of her arms. A white sash at her waist. Black hakama trousers. Traditional cloth shoes, white socks drawn up at the ankles. Standing there, she had almost no presence at all, not because her Reiatsu was suppressed, but because her whole being had simply dissolved into the grove. A leaf on pine needles. A shadow eaten by the canopy.

Soi Fon. Member of the Executive Militia of the Onmitsukidō.

"Lady Yoruichi." Her voice was barely above a breath, but the tension in it was unmistakable, it was almost an accusation. "Who was that?"

Yoruichi didn't turn around. She raised both arms in a long, lazy stretch, ankles crossed, completely at ease, the same as she'd been talking to Seijūrō.

"A Kidō teacher at the Shin'ō Academy." Offhand.

"This subordinate was not asking about his identity." Soi Fon's voice dropped further, pale gray eyes fixed on Yoruichi's back. "Why did Lady Yoruichi give him the dango?"

Yoruichi finally turned her head. Golden eyes found Soi Fon's face.

"Huh?"

Soi Fon's lips moved. Something was there, almost said. But no sound came. She dropped her gaze, straight bangs falling across half her face, expression hidden. Yoruichi watched her, something in her eyes going soft in a way that wasn't indulgence toward a subordinate, it was the helpless, gentle kind, the kind that only comes out for someone close enough to earn it.

"Let's go." Yoruichi straightened, bare feet pressing into the pine needles, and walked deeper into the grove without looking back.

I have a feeling he's going to be someone even more insufferable than Kisuke Urahara.

So thought Soi Fon.

➤ Next: Seven Bends — The Conversation