In the days that followed, Kotetsu Isane made a deliberate effort to avoid Shin. Even when they happened to cross paths, she'd only nod awkwardly and flee without a word.
Shin didn't push. He wasn't surprised—he simply let things run their course.
He soon found time to visit the 13th Division, where he met with Shiba Kaien.
"A sparring session?"
Kaien looked visibly surprised after hearing Shin's reason for coming.
"Just a friendly exchange between divisions," Shin clarified.
Kaien found it intriguing.
"Why the sudden idea? I mean… you're from the 4th Division. Can you even win in a fight?"
"Winning doesn't matter right now. Losses lead to growth. I believe one day, we'll win."
Kaien considered it and nodded.
"That's fair. When do you want to do it? Any rules about who can participate?"
"Beginning of next month. Bring whoever you want—seated officers or regular squad members."
"Got it. Count me in."
Division-on-division sparring was rare in the Gotei 13. Not because it was forbidden, but because inter-division comparisons were usually under-the-table—kept discreet to avoid stirring trouble. The laws of the Seireitei were strict.
Kaien, however, saw what Shin was trying to do—he wanted to change the 4th Division's reputation—and he was more than happy to help.
As they were speaking, a figure approached.
"Captain," Kaien greeted immediately.
"Captain Ukitake," Shin added with a respectful bow.
The man who approached was none other than Ukitake Jūshirō, captain of the 13th Division. He gave Shin a warm smile.
"Shin-kun, was it? What brings you to our division today?"
Kaien briefly explained the idea of sparring exchanges.
Ukitake listened and then nodded with a soft chuckle.
"I have no objections. You can leave the matter in Kaien's hands."
It was just a friendly match, after all. Most squad business in the 13th was handled by Kaien already, and Ukitake trusted him completely.
He turned to Kaien.
"I won't be at this afternoon's meeting. I need to step out for a bit."
"Understood," Kaien replied.
Then Kaien turned back to Shin with a grin.
"Hey Shin, want to come with me?"
Shin blinked.
"Where?"
"The Men's Shinigami Association meeting."
"The what?"
"Brand new association," Kaien said cheerfully. "Vice-captain of the 7th, Iba Tetsuzaemon, is the president. We'd be glad to have you. Your squadmate Iemura is a member too."
The Men's Shinigami Association?
Shin tried to remember. Yeah, it existed—barely. One of the lowest-profile groups in the Seireitei. They didn't even have a proper office, and they were constantly being crushed under the heel of the far more powerful Women's Association.
"I'll think about it," Shin replied cautiously.
Kaien grinned wider, turning up his recruiting charm.
"You know our Captain's a member too, right? Think carefully before you say no~"
Shin: "…"
Ukitake simply laughed—then broke into a cough mid-chuckle.
The Men's Association had no grand cause, unlike the Women's Association, which was founded to advance female rights in Soul Society. For men, whose rights weren't in jeopardy, it was more like a gathering of like-minded hobbyists. Ukitake had only joined to give them face. The group hadn't achieved much of anything since its creation.
Shin wasn't remotely interested.
But as he watched Ukitake cough, something shifted.
"Captain Ukitake… is your health okay?"
"It's fine," Ukitake waved it off. "Old problem."
He had a severe chronic illness that made him cough frequently, sometimes violently enough to interfere with combat or even consciousness.
Rumors had long painted him as "sickly and frail."
Shin remembered why: Ukitake had fallen deathly ill as a child, and just as he was nearing death, he was saved by a local deity from the Rukongai's Reverse Bone District—a divine being named Mimihagi, the Right Arm of the Soul King.
Mimihagi accepted a sacrifice in exchange for healing. In Ukitake's case, it had been his lungs.
The Soul King's right arm represented stopping, and though it saved his life, it also froze his lungs in the state they'd been in during his childhood illness—unable to heal, unable to worsen. He lived, but never fully recovered.
Almost no one in Soul Society knew this.
"Has no one tried to cure it?" Shin asked softly.
"Many have," Ukitake said with a rueful smile. "Even Captain Unohana has looked into it. But it's not something that can be healed."
He had long accepted it.
But Shin didn't back down.
"Captain Ukitake, maybe I could try."
Ukitake paused, startled.
"You didn't hear me just now? Even Captain Unohana couldn't—"
"My Zanpakutō is of the Kaidō type," Shin cut in. "I've studied healing extensively. I'm not saying I'm stronger than her—but maybe I've taken a different path. Your illness doesn't feel hopeless to me."
Kaien raised an eyebrow.
"You serious?"
Ukitake looked skeptical.
"It's not just a lung disease, Shin-kun…"
"I know. But if you'll allow me to examine you, I'll give it everything I've got."
Kaien gave Ukitake a look.
"Captain, why not let him try? Who knows—his Zanpakutō might have some unexpected ability."
Ukitake gave a long, quiet sigh, then finally relented.
"Alright. But I don't have time right now. If you're free tonight, come by."
"I will," Shin replied.
After Ukitake left, Kaien asked:
"You're really confident about this?"
"I haven't even examined him yet."
"You realize your own captain couldn't cure him either."
"He mentioned that."
Kaien looked doubtful, but intrigued.
"Alright. I'll be waiting."
Later that day, Shin returned to the 4th Division and went straight to Unohana's office. He brought up Ukitake's condition.
"Why bring that up all of a sudden?" she asked, surprised.
"I visited the 13th today," he replied calmly. "I want to try treating him."
Unohana's eyes flickered.
"You really want to?"
"I know it's not a normal illness," he said. "It feels more like… a rule."
Unohana froze. Her eyes narrowed slightly.
"You saw through it?"
"More or less."
"And you still want to try?"
"I do."
Unohana stared at him for a long moment before smiling faintly.
"If you manage to cure him, it would be a great service to all of Soul Society."
Shin grinned.
"That's the idea."
That evening, he returned to the 13th Division alone.
Kaien was waiting for him. They hadn't told anyone else.
In the captain's office, Shin found Ukitake with two others: Kotetsu Kiyone (Isane's younger sister) and Sentarō Kotsubaki—both 3rd Seats of the 13th Division.
"Captain, Shin's here."
Ukitake looked up from his papers with a smile.
"Ah, come in."
Kaien shot a look at the other two and subtly gestured. They nodded and left, closing the door behind them.
"Who was that?" Kiyone asked curiously. "Isn't he the 3rd Seat from 4th Division? What's he doing here?"
"Official business," Kaien said simply.
Inside, Ukitake was still flipping through documents. Shin waited quietly.
Eventually, Ukitake closed the last folder and looked up.
"You came alone? Didn't bring any tools or equipment?"
"For this," Shin said, "conventional medical tools won't help."
Ukitake chuckled.
"Already making declarations before you've even examined me?"
They sat by a low table. Ukitake unbuttoned his robe to reveal his chest.
He was pale and thin. His ribs were clearly visible.
Shin placed a hand on his chest and channeled healing reiryoku inward.
After a moment, he pulled his hand away, silent.
Ukitake mistook the silence for resignation.
"Tough, right? Don't worry. Even Captain Unohana couldn't do anything. It's not going to kill me, anyway."
But Shin suddenly spoke.
"Captain Ukitake."
"Yes?"
"Do you want to be cured… or not?"
Ukitake froze—then his expression began to shift.