Upper One in Demon Slayer is Kokushibo, a former Demon Slayer who became a demon after turning against humanity, and the most powerful of the Twelve Kizuki.
One of the most formidable demons in the series is Upper One – a mysterious and terrifying figure that plays a crucial role in the battle against the Demon Slayer Corps.
In this article, MangaNato dive deep into who is Upper One in Demon Slayer, exploring his identity, role in the story, and how his presence impacts the series.
Who is Upper One in Demon Slayer?
Upper One is one of the highest-ranking demons in the Twelve Kizuki, a group of demons directly under Muzan Kibutsuji, the leader of all demons.
Known for their immense power, each member of the Twelve Kizuki has a number associated with their rank, and Upper One holds the highest rank among them, making him a significant threat to the Demon Slayer Corps.

Who is the Upper One Demon?
The identity of Upper One is closely tied to one of the most powerful demons in the Demon Slayer universe. However, Upper One is shrouded in mystery for much of the series.
It is revealed later in the story that Upper One is actually Kokushibo, a former human who was once a member of the Demon Slayer Corps.
As Kokushibo, he becomes a demon after accepting Muzan’s offer, thus obtaining immense power but also losing his humanity in the process.
Kokushibo was originally a man named Michikatsu Tsugikuni, the older brother of Yoriichi Tsugikuni, the legendary swordsman known for his mastery of the Sun Breathing techniques.
While Yoriichi became the greatest swordsman in history, Kokushibo struggled with jealousy and fear of his own mortality.
This feeling led him to betray his humanity and turn into a demon, adopting the name Kokushibo. As a demon, Kokushibo gained extraordinary power, eventually becoming Upper One in the Twelve Kizuki.
Kokushibo’s transformation into a demon highlights the tragedy of his character. His jealousy and obsession with power ultimately led to his downfall, turning him into one of the most terrifying figures in Demon Slayer.
Kokushibo’s role in Demon Slayer
His strength and abilities
As Upper One, Kokushibo is considered one of the strongest demons in existence.
His demon abilities far surpass those of many other Kizuki members. Kokushibo possesses incredible swordsmanship, using his proficiency with the sword and his Demon Art to overwhelm his enemies.
His fighting style is a terrifying combination of speed, strength, and precision, making him a formidable adversary for any Demon Slayer.
His mastery of the Moon Breathing techniques, a derivative of Sun Breathing, allows him to fight with exceptional efficiency.
The power of Moon Breathing is enhanced by Kokushibo’s deep knowledge of combat and his ability to use multiple swords simultaneously.
Kokushibo’s impact on the story
Kokushibo’s role as Upper One makes him a significant threat to the Demon Slayer Corps, especially in the final arc of the series.
His battle against the Hashira, particularly Mitsuri Kanroji and Muichiro Tokito, highlights his immense strength and intelligence.
Kokushibo’s fight with Tanjiro Kamado and Yoriichi Tsugikuni’s legacy adds emotional depth to his character, showcasing his inner conflict, remorse, and desire for recognition.
Kokushibo’s connection to the Tsugikuni family
One of the most significant aspects of Kokushibo’s character is his relationship to the Tsugikuni family, particularly his younger brother, Yoriichi Tsugikuni, the creator of the Sun Breathing techniques.
Kokushibo’s deep jealousy toward his brother, who was born with unmatched talent, plays a critical role in his eventual decision to abandon humanity and accept Muzan’s offer.
Kokushibo’s relationship with his brother shapes his motivations, as he becomes consumed by the desire to surpass Yoriichi’s legacy.
Despite his demonic transformation, Kokushibo is haunted by his failure to protect his brother’s honor and to overcome the legacy of the Sun Breathing techniques.

Why is Upper One (Kokushibo) important in Demon Slayer?
Kokushibo’s role in Muzan’s plan
As the leader of the Twelve Kizuki, Muzan Kibutsuji relies heavily on Kokushibo to execute his plans for demon domination.
Kokushibo’s strength and intelligence make him one of Muzan’s most trusted followers, and his rise to Upper One demonstrates the power and influence Muzan can bestow on those who serve him loyally.
In the final battle against Kokushibo, the Demon Slayer Corps faces one of their toughest challenges yet.
Kokushibo’s involvement in the battle symbolizes the culmination of years of fighting and loss, making his defeat a pivotal moment in the series.
Kokushibo’s symbolism in the story
Kokushibo’s transformation from a Demon Slayer to a demon serves as a tragic symbol of the consequences of jealousy and unchecked ambition.
His internal conflict, rooted in his feelings toward his brother and his own power, adds layers of complexity to his character.
Despite his villainous nature, Kokushibo’s backstory reflects the sorrow and regret that ultimately define his character.
His relentless pursuit of power and the consequences of his actions are a core aspect of Demon Slayer’s themes of sacrifice, redemption, and the duality of good and evil.

FAQs: Who Is Upper One in Demon Slayer?
Below are some frequently asked questions about Who is Upper One in Demon Slayer, shedding light on this powerful demon’s role in the series and his connection to Who is the main character in Demon Slayer, Tanjiro Kamado.
Who is the main character in Demon Slayer?
The main character in Demon Slayer is Tanjiro Kamado, whose quest to avenge his family and find a cure for his sister, Nezuko, forms the core of the series.
What are Kokushibo’s abilities?
Kokushibo is a master swordsman, using Moon Breathing techniques and his unique demon powers to overwhelm enemies. His strength and speed make him a formidable opponent.
How did Kokushibo become a demon?
Kokushibo, born as Michikatsu Tsugikuni, was a skilled swordsman who turned into a demon after his jealousy of his brother, Yoriichi Tsugikuni, led him to seek immortality and power by accepting Muzan’s offer.
Why is Kokushibo so important in Demon Slayer?
Kokushibo is crucial because he is the highest-ranking demon in the Twelve Kizuki, and his battle with the Demon Slayer Corps is central to the series’ final arc.
What is Kokushibo’s connection to Tanjiro?
Kokushibo’s battle with Tanjiro is significant as it ties into Yoriichi’s legacy, with Tanjiro being the one to carry the torch of the Sun Breathing techniques that Kokushibo had once abandoned.
Who is Upper One in Demon Slayer? Upper One refers to Kokushibo, the most powerful of the Twelve Kizuki demons.
A tragic figure, Kokushibo was once a member of the Demon Slayer Corps before becoming Muzan’s right-hand demon. His rise to power and complex backstory, including his relationship with his brother, make him a key character.
To learn more about Kokushibo and the Twelve Kizuki, check out the latest chapters and updates on MangaNato!
