Upper Moon 6 is one of the most powerful demons in the Demon Slayer manga and anime series. He is a member of the Twelve Kizuki, Muzan Kibutsuji’s elite group of demons. In this article, we will take a deep dive into everything you need to know about Upper Moon 6 – his powers, his backstory, his personality, and more.
What is the Twelve Kizuki?
The Twelve Kizuki are the twelve most powerful demons under Muzan Kibutsuji’s command. They are split into two groups – the Upper Moons and the Lower Moons. The Upper Moons are the strongest of all the demons, with Upper Moon One being the most powerful. The Lower Moons are still incredibly strong but not on the same level as the Upper Moons.
The Twelve Kizuki serve to carry out Muzan’s will and help him achieve his goal of annihilating all demon slayers and conquering the world. They each have their own territories and are free to do as they wish as long as they obey Muzan’s orders. The rankings of the Twelve Kizuki are constantly shifting, with Lower Moons being replaced if they are killed by demon slayers. Even Upper Moons can be replaced if Muzan finds another demon that he deems to be stronger.
Upper Moon Six’s Backstory
Not much is known about Upper Moon Six’s life before becoming a demon. In the manga, it is revealed that his name was Kaigaku when he was still a human. He was born into a family of shrine wardens and was raised at a temple. From a young age, Kaigaku was recognized to have impressive spiritual abilities and the potential to become a demon slayer.
When Kaigaku was 12 years old, he was sent to the Demon Slayer Corps to begin his training. He was talented but had an abrasive, arrogant personality. He saw Zenitsu Agatsuma at the training grounds, who was always sick and lagging behind. Kaigaku bullied Zenitsu relentlessly, feeling superior to him.
Two years later, Kaigaku encountered a Horned Demon while on a mission. Instead of slaying it, he proposed that he would serve under the demon if he was turned into a demon himself. The demon agreed and turned Kaigaku, drawn to his unusually strong spiritual power. Kaigaku fully embraced his new demonic abilities and abandoned the Demon Slayer Corps.
Becoming Upper Moon Six
After becoming a demon, Kaigaku gained notoriety for hunting and eating humans with no discrimination. His actions drew the attention of the Twelve Kizuki, and he was recruited by Kokushibo, Upper Moon One at the time. Impressed by Kaigaku’s bloodlust and power, Kokushibo inducted him into the Twelve Kizuki as Lower Moon Six.
Over time, Kaigaku consumed more humans and continued to refine his skills and grow stronger. 100 years after joining the Twelve Kizuki, he had powered up enough to be promoted to Upper Moon Six, replacing the former holder of that rank.
As Upper Moon Six, Kaigaku was granted far more authority and responsibility. He was given his own territory and minions to command. Muzan had high hopes that Kaigaku would be able to retain his Upper Moon position for many years to come.
Personality and Behavior
As a human and demon slayer trainee, Kaigaku was ambitious, talented, but also arrogant. He bullied Zenitsu despite them both training under the same master. As a demon, these negative personality traits were amplified even further. Kaigaku is self-centered and sadistic. He has an insatiable hunger for slaughtering and devouring humans.
In his first encounter with Zenitsu after becoming a demon, Kaigaku mocks him and calls him worthless. He delights in having surpassed someone who was once above him. His craving for power and status drives him to elongate his survival and immortality as an Upper Moon demon.
Despite his brashness, Kaigaku has shown himself to be cautious. In stressful situations, he uses tactics like taking hostages to better his odds against demon slayers. He relies more on deceit and manipulation than brute strength against skilled opponents.
Upper Moon Six’s Powers and Abilities
As an Upper Moon demon, Kaigaku boasts superhuman strength, speed, stamina, and durability. He can easily decapitate humans and slice through bones with his hands. Like all demons, he has advanced regeneration, allowing him to recover from grievous injuries very rapidly.
Kaigaku’s main combat ability is generating powerful sound waves and vibrations. He does this by using a handheld tuning fork weapon. When struck with the tuning fork, he produces thunderclap-like blasts of sound that can obliterate everything in their path. He can focus the sound waves into concentrated beams capable of piercing through flesh.
In addition, Kaigaku has demonstrated sound wave abilities including:
- Generating omnidirectional explosions of sound that affect a wide area.
- Creating sound barriers that defend against enemy attacks.
- Levitating and moving quickly by bouncing on sound waves.
- Using sound to disorient opponents and damage their sense of hearing.
Kaigaku’s skill set makes him a threat at any range. The vibrations from his tuning fork can also be used to deflect swords and other weapons. This forces enemies to get up close to attack him.
Battle Against Zenitsu Agatsuma
Kaigaku’s deepest desire is to get revenge on Zenitsu Agatsuma for looking down on him when they trained together. After becoming Upper Moon Six, he encounters Zenitsu and happily tries to kill him. However, Zenitsu has also gained powerful abilities as a demon slayer.
Zenitsu’s lightning breathing technique makes him incredibly fast and dangerous. He manages to outpace Kaigaku and slice off his limbs before Kaigaku can react. A desperate Kaigaku takes a woman hostage to force Zenitsu to stop attacking him. But Zenitsu uses his speed to kill Kaigaku before he can harm the hostage.
In his dying breaths, Kaigaku continues to mock Zenitsu and says he has no talent. But Zenitsu refutes this by explaining how hard he worked and trained to reach his level of skill. Kaigaku dies in disbelief that he was surpassed by someone he considered a failure.
Conclusion
Upper Moon Six, Kaigaku, had natural talents but let his arrogance and ambition lead him down a dark path. As a demon, his negative personality traits were amplified, making him a merciless killing machine. Despite becoming one of the highest-ranked demons under Muzan, Kaigaku’s obsession with vengeance against Zenitsu led to his downfall. His story shows how power gained through deceit and cruelty can ultimately lead to one’s destruction.