Before Renji became lieutenant, the position was held by a predecessor (not clearly named in canon).
*******
Gin-san, may I ask what you called me here for?"
"Ah, Renji-kun! There you are." The always relaxed Gin Ginjiro leaned back, arms folded behind his head. "I've got good news for ya. I'm planning to step down as Vice-Captain of the Sixth Division, so I recommended you to Captain Kuchiki."
"E-Eh? Vice-Captain… me?" Abarai Renji's eyes widened in disbelief.
"That's right. You've already achieved Shikai, haven't you? I believe you've got what it takes to fill my shoes."
Ginjiro grinned. "So? What do you think? Want the spot?"
Renji's gaze drifted to the Vice-Captain badge on Ginjiro's shoulder. A familiar pressure settled in his chest as the image of a silent noble with cold eyes—Kuchiki Byakuya—flashed in his mind. And then, for a brief moment, he remembered him… the boy with sharp eyes and a mouth that never shut up—Amamiya Miyako.
Clenching his fists, Renji nodded. "Please… let me give it a shot!"
"Haha, good answer. Come with me. Captain Kuchiki is waiting."
—
Meanwhile, over at the Thirteenth Division barracks…
Kiyone Kotetsu and Sentarō Kotsubaki had just wrapped up their paperwork and were heading back to rest. That was when they saw a familiar—and chaotic—scene.
"Mou! There goes Vice-Captain Amamiya again, running for his life," Kiyone sighed dramatically.
"And Kuchiki-san's right on his heels! Again?" Sentarō blinked.
"You don't know yet? Hmph. Sit tight, I've got juicy intel." Kiyone's face lit up with gossip-mode intensity.
"What is it this time?"
"Yesterday, Vice-Captain Amamiya took Rukia-san's duty shift. And guess what~?" Kiyone leaned closer.
"What?"
"They came back together to the barracks, and their hands were clasped—the whole way! So lovey-dovey!"
"Ehh?! S-Seriously?! Could it be that those two are—"
"Hehe, I wouldn't go that far, but you can feel it, right? The sparks?" Kiyone beamed.
"Well… now that you mention it, Rukia-san has been smiling more since Amamiya joined our squad. She's not as gloomy as she used to be."
"Right?! It's all thanks to Vice-Captain Amamiya that she's come back to life, so to speak."
"Ughhh, I can't take it anymore! Those two… I fully support this ship!" Kiyone squealed, hands cupping her cheeks.
"Oi, keep it down! They'll hear you!" Sentarō whispered frantically.
Too late.
Rukia had already stopped mid-chase, standing stock-still with her head bowed. She'd overheard every word.
"R-Rukia?" Amamiya Miyako slowed to a stop, a little concerned. "You okay?"
He approached her carefully.
She didn't look up—until he was close enough.
"BAKA!"
With zero hesitation, she delivered a full-powered kick to Miyako's stomach, launching him backward.
As Amamiya lay groaning on the ground, Rukia spun on her heel and stormed off, cheeks flushed redder than a tomato.
"She's gone," Amamiya muttered, scratching his head.
At that moment, Kiyone Kotetsu and Sentarō Kotsubaki came running over with wide eyes.
"Vice Captain Amamiya, are you alright?" Kiyone asked with barely concealed amusement. "What in the world did you do to Kuchiki-san?"
"Oi, I'm not helping you if you made her mad," she added, folding her arms.
"Trying to slack off already, huh? You only just became Vice Captain!" Sentarō exclaimed, puffing out his chest with mock outrage.
"Aha ha ha… You two really don't hold back." Miyako stood up, patting dust off his uniform, trying his best to laugh it off.
"I knew it! Your plan has been exposed!" Sentarō said dramatically, pointing at Miyako like a kabuki actor.
Miyako's tone shifted to one of mock sincerity. "You wound me. I trust the both of you so deeply—I'm thinking of what's best for the division. Truly."
"You're making excuses again!" Kiyone huffed, not buying it. "We're not falling for your tricks anymore!"
"Yare yare…" Miyako sighed, putting on a look of exaggerated resignation. "Alright then, let's strike a deal. I'll take full charge of all Thirteenth Division duties. You two won't even need to step into the office. That way, Captain Ukitake won't have to overexert himself, and you'll both be free to support him directly. Sound fair?"
The two Third Seats looked at each other. Their lips were tight. They weren't answering right away.
Kiyone clenched her fists. If I can't stay by Captain Ukitake's side… that'd be worse than dying!
"You two know about the Captain's condition," Miyako pressed gently. "With Kiyone watching over him, and Sentarō handling daily tasks, we'll be stronger as a team. And me? I'll be the sword of the division. Anyone who dares look down on the Thirteenth Division—I'll silence them with force."
He raised his hand solemnly, as if taking a vow. "I promise to defend the pride of our division."
"Vice Captain Amamiya!" the two suddenly shouted in unison, their eyes glittering with emotion.
"I'm so sorry, Vice Captain! I misunderstood you completely…" Kiyone said, eyes trembling.
"Same here! I judged you too quickly… sniff…" Sentarō practically wiped away a non-existent tear, dramatically touched.
"Let's do our best together, Kiyone, Sentarō." Miyako placed a hand on each of their shoulders and flashed his trademark grin. "Captain Ukitake trusts you… and so do I."
They nodded with fiery passion, completely unaware they'd been played like a shamisen by Miyako.
After successfully winning over the two, Amamiya Miyako waved and headed back toward the barracks. The sparring match with Rukia had drained more energy than expected.
Did he feel guilty for tricking them?
Not at all.
Even if it was a little devious, what he said wasn't wrong. Kiyone and Sentarō already wanted to be near the Captain, and they were better at handling daily affairs than most. As for Miyako himself—he needed time. Time to train. Time to grow stronger.
It was a win-win. A flawless victory, really.
Later that night, Miyako sat cross-legged in his quarters, twin Zanpakutō laid across his knees.
The training with Rukia had sparked something in him. He had to revisit his inner world—figure out just what had changed since he'd learned his Zanpakutō's name. And maybe… take the next step.
"Bankai…" he murmured.
He closed his eyes. His breathing slowed. In an instant, his consciousness faded—and he sank into the familiar darkness of his inner world.
The moon hung high above the quiet street. Cool blue light spilled across cracked pavement. Everything was eerily still.
Just like before.
But then—his eyes widened.
Standing atop a nearby telephone pole wasn't the black-haired, white-robed figure he expected.
It was someone… else.
Wild white hair danced in the wind. A black tattered haori clung to his form, blending into the night. And his face—his face was twisted in unmistakable disgust.
The boy looked just like him. And yet… completely different.
"Who…?" Miyako muttered, heart pounding. "Zetsun…?"
"Don't call me by that name, you spineless coward!" the white-haired figure barked, voice like a knife.
"W-What…?"
The mysterious Zanpakutō spirit clenched his fists. His eyes burned with resentment. Then, after a tense silence, he turned his head aside, biting back his words.
As if he were holding something in.