Zenitsu listened to the sounds inside from outside the house; there were two voices inside.
One is his grandfather, Kuwashima Jigoro.
The other one is...
Zenitsu's expression gradually changed. His ears were super senses, no less than Tanjiro's nose. He could not only clearly hear sounds from a great distance or very faint sounds, but he could even distinguish the difference in breathing between humans and other creatures.
"Old man! Do I know how many people have looked down on me because I don't know the First Form?! Zenitsu can master the First Form, there's no reason why I can't learn it. You must have done something to it!"
"What are you talking about? How could I possibly treat you and Zenitsu differently? Zenitsu is my prized disciple, and so are you..."
"You think I'd believe that?!"
Thunder Breathing has a total of six different sword techniques, which are not only few in number but also quite different from other breathing sword techniques.
For example, in Flame Breathing and Water Breathing, the most precise sword technique is the final form, while in Thunder Breathing, the most crucial technique is the initial form.
The sounds coming from inside the house gradually became noisy. Zenitsu outside could no longer hold back. He pushed open the unlocked door and stared into the house through gritted teeth.
His grandfather, Kuwajima Jigoro, collapsed to the ground, while standing in front of him was Zenitsu's senior apprentice, Kaigaku.
"Kaigaku! How did you turn into a demon?!" Zenitsu roared angrily at his once respected senior brother, Kaigaku.
In his sight, Kaigaku was no longer human. Demon fangs protruded from his mouth, his ears were as sharp as bat ears, his skin was pale, and his face was covered with black, tiger-striped demon markings.
Zenitsu was shocked and furious at the sight. If Chinatsu had seen this, she would have been surprised as well, since in the original story, Kaigaku became a demon after meeting Kokushibo, and he had already defeated Kokushibo.
The original text describes how Kaigaku encountered Kokushibo during a mission, and all the other swordsmen who were with him were instantly killed.
Terrified, Kaigaku knelt down and begged for mercy. Kokushibo saw a trace of his former self in Kaigaku, the one who had once tried to become stronger at all costs. In the end, he gave him demon blood, helping him become a demon.
However, the original work does not explicitly state when Kaigaku became a demon. It only states that Zenitsu received news a few days after the Swordsmith Village arc that Kaigaku had become a demon and that his grandfather had committed seppuku.
It could be the convergence of timelines, or Kaigaku might have already become a demon before Chinatsu defeated Kokushibo. Information transmission also takes time, so it's possible that Kaigaku became a demon before the Swordsmith Village storyline even began.
Anyway, Kaigaku has already become a demon, but unlike in the original work, he doesn't have the mark of "Upper Moon Six" engraved in his pupils.
As Zenitsu suddenly barged in, Kaigaku turned to look at him. When he realized that the person who had come was Zenitsu, a look of annoyance first appeared on his face, followed by a mocking smile.
"It's you, Zenitsu, you good-for-nothing. I heard you recently participated in the battle to defeat the Upper Moons? No doubt about it, you probably colluded with the Pillars and high-ranking swordsmen to fish in troubled waters. After all, you only know one [First Form], you're just a piece of trash!"
Kaigaku looked at Zenitsu, who was looking furious, and said with a mocking smile, completely disregarding Zenitsu.
However, Zenitsu didn't take Kaigaku seriously. His gaze was more focused on his grandfather behind Kaigaku. After realizing that his grandfather didn't have any particularly serious injuries, he breathed a sigh of relief and then turned his attention back to Kaigaku.
"Let me make this clear beforehand: the moment you become a ghost, you are no longer my respected senior brother. Also, if I am a piece of trash, then you are a piece of trash too!"
Zenitsu's aura was completely different from his usual timid demeanor, and even the previously arrogant Kaigaku was taken aback by Zenitsu's presence.
Wait a minute? Am I scared by Zenitsu?
Zenitsu? Impossible!!!
Realizing what had happened, Kaigaku felt a surge of shame and anger, and he drew the sword from its sheath at his waist.
This is not an ordinary Nichirin Blade, but a blade formed from his own demonic flesh and blood, just like Kokushibo's method.
"Thunder Breathing - Fourth Form - Far Thunder!!!"
As Kaiyue forcefully swung the sword in his hand, black lightning flashed out in all directions from him.
One of the black lightning bolts struck the wall of the mansion, and with a loud "bang!!!", the wall instantly shattered into pieces of rubble.
Kaigaku looked at his current power with excitement, because the power he was unleashing now far surpassed that of his human self.
This is the power of demons! Even a Pillar might not be my match now!
Kaigaku thought this excitedly, while Zenitsu, standing in front of him, dodged the lightning bolts that were not targeting any specific object with exquisite agility.
Zenitsu kept his head down, maintaining a high level of Thunder Breathing, and golden lightning ripples flickered on the surface of his body.
"Thunder Breathing - First Form: Thunderclap Flash - Divine Speed!"
In an instant! A golden light flashed through Kaigaku's vision, and Zenitsu, who was in front of him just a second ago, was now behind him, next to Kuwajima Jigoro.
Kaigaku's eyes trembled, his pupils filled with envy, because he did not know the "First Form". Compared with the "First Form", the other five forms were just auxiliary techniques.
Just as Kaigaku was about to turn around and look at Zenitsu, the delayed damage finally arrived. His head was cut in two horizontally. Although it was not fatal, he had only recently become a demon, and his pain receptors were still very sharp. This level of pain caused him to scream in agony.
Kuwajima Jigoro watched this scene, his expression a mixture of shock and relief as he looked at Zenitsu beside him.
Zenitsu turned his sharp eyes to look at Kaigaku, who was screaming in agony with half his head gone, while the Nichirin Blade in his hand flashed with golden thunderous crackling sounds.
Did he increase his strength by turning into a demon and eating people?
Zenitsu not only mastered "Thunder Breathing: Normal Mode," but also underwent round after round of grueling training and fought against Upper Moon 6.5, Daki.
Zenitsu's strength was accumulated little by little through countless trials and tribulations; how could he be no match for Kaigaku, who was arrogant and conceited, and thought he had taken a shortcut?
Kaigaku's half-head slowly grew back, but at this moment, Zenitsu's appearance gradually became distorted in Kaigaku's eyes.
Zenitsu, in front of Kaigaku, once again performed the "First Form" and coldly said, "With the next strike, I will sever your neck!"
………………
Continue read on readnovelmtl.com