The Hollow Poison spread rapidly. Within just a dozen seconds, Unohana's arm was already covered in terrifying black lines, wriggling beneath her skin like countless worms.
"This isn't Adjuchas-level Hollow Poison!" Unohana immediately realized something was wrong. Yet the poison had been personally prepared by her just last week—this wasn't supposed to happen.
She had extracted the Hollow Poison from a Shinigami who had been infected. Judging by the severity of that Shinigami's injuries, it should have been Adjuchas-level.
Unohana continued suppressing the poison with her Reiatsu. Soon, a sheen of sweat appeared on her smooth forehead.
The immense Reiatsu of a captain-level Shinigami reverberated through the classroom. Everyone felt as if the air had been sucked out of their lungs—a suffocating pressure descended, as if a mountain was weighing down on their backs.
"Captain Unohana!"
"This is bad—Captain Unohana can't suppress the Hollow Poison!"
The other Kaido instructors quickly caught on. The situation clearly wasn't something Unohana had anticipated.
Despite the crushing pressure, several instructors rushed forward to check on her.
Unohana rolled up her sleeve—her entire left arm had turned black, and the dark lines had even spread to her shoulder. Fortunately, with her full power suppressing it, she had temporarily stopped the poison's advance.
But this state couldn't be maintained for long. Once her condition declined, she would no longer be able to contain the poison.
"Captain Unohana, do you still have enough room to treat the poison?" Department Head Yamada asked anxiously.
"No... I have to keep suppressing the Hollow Poison with my Reiatsu... I can't spare any energy to use Kaido," Unohana said, frowning deeply.
Treating Hollow Poison with Kaido was already a delicate task. While suppressing the poison at full strength, she couldn't use Kaido to purge it.
"Then let me help. I can handle Adjuchas-level Hollow Poison," Yamada said, relieved that he might be able to assist and avoid a major teaching accident.
"No," Unohana said firmly.
"Captain Unohana, this is Hollow Poison! This isn't something to take lightly—just let me do it!" Yamada insisted.
"Department Head Yamada, I don't think this is Adjuchas-level Hollow Poison," Nanatsuki said seriously.
"Katori-sensei, what do you mean by that?" Yamada frowned, his opinion of this Swordsmanship Department teacher dropping quickly.
"With Captain Unohana's strength, suppressing Adjuchas-level Hollow Poison wouldn't be a problem," Nanatsuki replied promptly.
"He's right. I can suppress Adjuchas-level poison just fine... This is probably Vasto Lorde-level Hollow Poison," Unohana nodded.
She was surprised Nanatsuki had deduced that.
To reach such a conclusion required deep knowledge of both Hollow Poison and her own strength.
"What?!" Yamada was horrified. "You used Vasto Lorde-level poison for this demonstration?!"
He couldn't believe Unohana had used poison from a Vasto Lorde-class Hollow in a teaching experiment.
Vasto Lorde-class Hollows were the most elite among all Menos. Some were even stronger than young captains. Injecting Hollow Poison from one of them was practically suicide.
"The Hollow Poison I prepared wasn't like this..." Unohana muttered.
"But... I can't remove Vasto Lorde-level Hollow Poison either! What should we do now?!" Yamada was sweating profusely.
Unohana reached for her Zanpakutō. At this point, only its power might solve the problem.
"Captain Unohana, let me handle it," Nanatsuki suddenly said.
Her hand paused over her Zanpakutō.
"Katori-sensei, please don't make things worse!" Yamada shouted, practically having a stroke. The Fourth Division Captain might die inside the academy, and here came a swordsmanship teacher making jokes?!
"Maybe we should notify the other captains and see if they have a solution?" Kobayashi-sensei suggested.
"Katori-kun... Are you serious?" Unohana furrowed her brows.
"I've been studying Kaido nonstop to heal Batsu'unsai's Spiritual Pressure Core," Nanatsuki replied earnestly. "I can handle Vasto Lorde-level Hollow Poison."
He saw this as a perfect opportunity to show off his Kaido skills. If he succeeded, maybe he'd even get the chance to lead the Kaido Advanced Class.
"Katori-kun, I can suppress the poison for twenty more minutes. You have twenty minutes," Unohana decided to give him a chance.
From what she knew, Nanatsuki wasn't a reckless person.
If he failed, she could always use her Zanpakutō.
"Captain Unohana, you're really letting him mess around?! This is Vasto Lorde-level poison! We can't afford to waste time!" Yamada's head was spinning. He couldn't believe Unohana was putting her life in the hands of a Swordsmanship teacher with just a few years of Kaido training.
"Don't worry. If Katori-kun fails to purge the poison, I have a backup plan," Unohana said calmly.
Her assurance eased the tension slightly. Everyone turned their eyes to Nanatsuki, curious what this Swordsmanship teacher was capable of to earn such trust.
The Kaido Advanced Class classroom was equipped with surgical tables and instruments. Unohana lay down on one of them.
Nanatsuki picked up a scalpel. A thin layer of Reishi quickly coated its surface.
Hollow Poison was composed of corrupted Reishi—once it invaded a Shinigami's body, it devoured their own Reishi to grow stronger.
Nanatsuki's task now was to separate the infected Reishi from Unohana's body.
The scalpel sliced into her flesh, and black blood oozed out. When it hit the surgical table, it corroded a hole into it instantly.
Thankfully, the classroom was on the first floor. If that blood had fallen on a student or teacher, it might have killed them instantly.
After each incision, Nanatsuki removed the contaminated Reishi from the blade and replaced it with a fresh layer. The Hollow Poison quickly assimilated the old layer, requiring constant swaps throughout the procedure.
As the surgery continued, he carefully separated the infected Reishi. Black pus flowed endlessly from the wound.
Without a high enough level of Kaido, a healer couldn't keep up with the pace of the poison's spread during this step.
The students couldn't understand the intricacies—they only saw Nanatsuki's movements as smooth and fluid, fitting their image of a Kaido master.
But the other Kaido instructors knew the terrifying truth.
Yamada's expression shifted through shock and disbelief. From skepticism, to serious observation, to utter awe.
By the end, he was questioning his entire life.
'This new Swordsmanship teacher... is better at Kaido than me?!'
'Did he join the wrong department?!'
'With that kind of Kaido skill, why the hell is he teaching swordsmanship?!'