Kokushibo Demon Slayer Upper Moon 1 - Backstory And Powers Explained

Image source: © Koyoharu Gotouge / Shueisha, Aniplex, ufotable

Who is Kokushibo?

Kokushibo is a demon in the Kimetsu no Yaiba series and is known as the strongest demon in his entire demon life span and holds the rank of Upper Moon 1 in the 12 Kizuki.

Kokushibo became a demon around 400 years prior to the current timeline and since then he has remained the strongest demon ever made, and no one except Muzan and Yorichii can defeat him.

Kokushibo, when humans lived under the name Michikatsu. Michikatsu was born in the Sengoku era and was the elder twin of Yorichii. Michikatsu was born without the demon slayer mark, due to which his father chose him as the successor of his family.

Appearance

Kokushibo's most distinctive feature is his six eyes - three pairs arranged vertically on his face, each inscribed with "Upper Moon" and "One" in his sclera. His appearance combines traditional samurai aesthetics with horrifying demonic modifications: long spiky hair, flame-like markings reminiscent of his retained Demon Slayer Mark, and a flesh-based sword that extends from his own body.

Kokushibo Life as a Human:

Kokushibo, when humans lived under the name Michikatsu. Michikatsu was born in the sengoku era and was the elder twin of Yorichii. Michikatsu was born without the demon slayer mark, due to which his father chose him as the successor of his family and decided to kill Yorichii due to his mark but was spared due to his mother's request. After this, his father decided that Yorichii would be sent to a temple at the age of 10. Due to this discrimination between twins, Michikatsu was raised as the true heir of a prominent family, while his brother was raised the exact opposite of him. This led to Michikatsu thinking that he was superior to his younger brother, but he still loved and cared for his younger brother.

While Michikatsu received years of samurai training as the heir of his family, Yorichii never touched a sword until he was seven years old. Even after holding a sword for the first time, Yorichii defeated Michikatsu's tutor by dealing 4 strikes so fast that everyone was shocked. This shocked Michikatsu so much that he started to develop jealousy after seeing that his younger brother, whom he had misunderstood as a weak person, was so much stronger than him. After seeing Yorichii's strength, his father started changing his view of him and was thinking of making Yorichii the successor and sending Michikatsu to the temple in place of Yorichii. Michikatsu's view of his superiority was shattered, and he realised that he had to fill a huge gap in strength to surpass his younger brother.

Tragedy of brotherhood:

Despite being raised as superior to his younger twin brother, Michikatsu deeply loved and cared for Yorichii even after he thought that Yorichii was weak. Yorichii was treated horribly by his father, due to which Michikatsu gave him a flute, asking him to whistle whenever he is in trouble, and he would come for his help. This proves his deep love for his brother. This love was overshadowed by jealousy when Michikatsu saw Yorichii's exceptional skills as a swordsman and the fact that his thought of being superior was all but a delusion. Michikatsu's jealousy increased even more when his mother died and he found her diary. In her diary, it was stated that his mother was severely sick and was hiding this truth from everybody, and Yorichii was the only person in his family who knew it. Everyone thought that Yorichii is just a weak, mute and deaf child who always clung to his mother due to his weakness, but the real reason was that he always supported his mother in her illness and was always looking after her and taking care of her. This made his jealousy deeper and he started feeling more inferior.

Demon Slayer mark awakening:

Yorichii was born with the demon slayer world, but this was not the case with Michikatsu. Michikatsu went through serious training under Yorichii, learning sun breathing style and through his hard efforts, he awakened his demon slayer mark, but was unable to master sun breathing style like his brother. Michikatsu then created his own style of breathing named Moon Breathing, which was the second most powerful breathing, but was still unsatisfied because Sun Breathing far surpassed it. A demon slayer mark makes a demon slayer extremely powerful, but at the cost of a shortened life span. While it may be powerful but it comes with a curse of death at the age of 25. This fear of death was one of the main reasons Michikatsu accepted the offer of becoming a demon.

Michikatsu's path into a demon's life:

Michikatsu was offered to become a demon by Muzan himself, who was terrified by Yorichii after his defeat. Michikatsu accepted this offer for the following reasons:

1. To avoid death at the age of 25 because of the demon slayer mark
2. To unlock his full potential through immortality and surpass his younger brother Yorichii.

It took 3 days of time for Michikatsu to transform into a demon, which is the longest in Demon Slayer world history. This shows his exceptional strength. After transforming into a demon, Michikatsu changed his name to Kokushibo and is now the strongest demon ever created by Muzan. The only people who surpassed Kokushibo while he was alive were Muzan and Yorichii.

Powers and Abilities Explained

Moon Breathing:

Moon Breathing: All 16 Forms Analyzed How Strong Is Kokushibo in Demon Slayer? Kokushibo possesses the most extensive breathing technique in the series, with 16 distinct Moon Breathing forms, each enhanced by his Blood Demon Art to create crescent-shaped energy blades: Notable Forms: First Form: Dark Moon, Evening Palace - Horizontal crescent slashes Seventh Form: Mirror of Misfortune, Moonlit - Massive shock-wave attacks Fourteenth Form: Catastrophe, Tenman Crescent Moon - Devastating whirlpool of slashes Sixteenth Form: Moonbow, Half Moon - Six enormous crater-creating slashes

Blood Demon Art: Flesh Sword Creation

Kokushibo's Blood Demon Art allows him to create and manipulate his sword from his own flesh and blood. This organic weapon can change size, sprout additional blades, and generate eyes along its surface for enhanced perception. The sword integrates seamlessly with his Moon Breathing, creating unpredictable attacks that vary in length and trajectory. Transparent World and Enhanced Senses His six eyes provide unprecedented battlefield awareness, combining with his Transparent World ability to see through opponents, predict movements, identify weaknesses, and assess combat capabilities instantly. This sensory advantage makes him nearly impossible to surprise and allows him to identify bloodline connections, such as recognizing Muichiro as his descendant. Combat Capabilities: Second only to Muzan in raw power 400+ years of battle experience Enhanced regeneration (can regrow his head) Multiple sensory advantages Unpredictable weapon modifications

Final Battle and Final Moments:

The final battle of Kokushibo took place in the Infinity Castle arc, where he fought a team of 4 demon slayers(Gyomie, Sanemi, Muichiro, Genya). This battle was epic, and through great efforts, the demon slayers decapitated Kokushibo but despite his severed head, his will to surpass his brother didn't let him die, and he started regenerating his head. After regenerating his head, he completely transformed into a monster-like being, which even he was ashamed of. Kokushibo, after seeing his monster appearance, decided to stop his regeneration and fade into nothingness. In his final moments, after he saw the flute which he gave to Yorichii in his childhood, he realised how his jealousy consumed him and he couldn't even remember his family's face and how he sacrificed everything to surpass Yorichii and still wasn't able to.

Also read The Final Reunion: Yorichii vs Kokushibo (upper moon one vs Strongest Demon Slayer)

Conclusion