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The Upper-Rank One Demons’ life is filled with regret, longing, and inferiority. From the start of his birth, he has always been compared to his younger brother and, as such, made it his mission to be better than him. But who is he really? Follow this guide as we go through the lifetime of who is the Upper Moon One in Demon Slayer.
Demon Slayer – Who is Upper Moon One?
There is much to unpack regarding the man called Upper Moon One Kokushibo. As you may already know, all Demons were once human; however, Kokushibo was not an ordinary human. Instead, he was a Demon Slayer. Kokushibo is the name he gave himself when Muzan turned him into a Demon. His human name is Tsugikuni Michikatsu, and he is the older twin of Tsugikuni Yoriichi, the strongest Demon Slayer.
This is where Kokushibo’s story begins, specifically because of his younger twin Yoriichi. You see, Kokushibo has always thought of his younger twin Yoriichi, to be inferior. Although both men are identical twins, Yoriichi’s Demon Slayer mark is seen as grotesque. As such, he was shunned by his family, and Kokushibo would risk beatings by his father to speak to Yoriichi.
However, this all changed when their mother died unexpectedly. After reading their mother’s diary, Kokushibo learns that Yoriichi has supported her throughout her illness, which was unknown to everyone. This greatly infuriated Kokushibo, and thus he now had a deep hatred for his brother. As he believed him to be inferior to him, this greatly impacted his views on his brother.
To rub salt into the wound, Kokushibo was even saved by Yoriichi when attacked by a Demon. However, when Kokushibo learned that Yoriichi had become much, much more powerful than himself, this hatred turned into a seething rage.
Kokushibo decides to become a Demon
Not one to let his little twin brother hog all the spotlight, Kokushibo also joins the Demon Slayer Corps to learn Sun Breathing. Unfortunately for him, he was unable to master this technique. While unable to use Sun Breathing, the most powerful Breathing Style in the Corps, Kokushibo was able to create Moon Breathing. Due to Kokushibo’s inferiority complex toward his younger brother, he soon turns to Muzan, who transforms him into the Upper Moon One Demon.
Kokushibo rationalizes to himself that, by turning into a Demon, he will be in peak condition to improve his Breathing Style, together with his Blood Demon Art. However, over sixty years have passed since Kokushibo last saw his brother. When they have their final dual, Yoriichi strikes so fast that Kokushibo can barely react and prevent himself from being beheaded.
Unfortunately for Kokushibo, a second strike from Yoriichi never came because he died of old age. So once again, Kokushibo is fuming with anger. Not only was he able to surpass his brother, but in his rage, he slashed his brother’s corpse due to his inferiority. Therefore, Kokushibo has made it his mission to develop his Moon Breathing Style (to spite his brother).
Demon Slayer – Upper Moon One meets his Descendent
Although Kokushibo spent most of his life feeling inferior to his brother Yoriichi, he could take a wife as he was from a prominent family. As such, we would go on to have descendants who are Yuichiro and Muichiro Tokito. We now understand why Muichiro is so powerful at fourteen years old; it’s because of his relation to Kokushibo.
The two will meet during the events of the Infinity Castle Arc. Once the battle has begun, Muichiro is transported to the same room as Kokushibo, who then notes a familiar feeling from Muichiro. After hearing his surname, Kokushibo notes that his human surname Tsugikuni has died out over the generations. But, he is still surprised and greatly impressed by Muichiro’s abilities.
However, after striking him down and gravely wounding him, he offers Muichiro to become a Demon. This will provide him with more power and heal his arm that was cut off. Unfortunately, Muichiro declines this offer and passes away. Though, he does regret killing his descendants.
Upper Moon One Kokushibo does meet his end later in Infitny Castle Arc, at the hands of Gyomei and Sanemi. This is where we learn he lived a life of regret and admits he only wanted to be like his younger brother Yoriichi.
And with that, we conclude this guide on who is the Upper Moon One in Kimetsu no Yaiba: Demon Slayer. If you enjoy the dark series, we have other guides that may interest you. Check out, Do Titans Still Exist In Attack on Titan? Or Who Are The Four Horsemen In Chainsaw Man?