In the world of Demon Slayer, we’ve met a ton of powerful characters. But some of the most powerful are the ones known as the Upper Moons. These characters are arguably the most dangerous group in the series. In today’s blog, we’re going to break down a character who has ever held the title of Upper Moon by covering everything you need to know—from his powers to his origins and other various facts. We will talk about the Upper Moon Number Six: Kaiaku. Depending on where you are in your Demon Slayer journey, this blog will contain spoilers, but I will keep any spoilers limited to what is necessary for each point made.
Upper Moon Number Six: Kaiaku
Kaiaku is the newest Upper Moon 6 of the series. In his past life, he was once a Demon Slayer before turning into a demon. His Blood Demon Art is electrokinesis, building upon his mastery of Thunder Breathing during his time as a Demon Slayer. When he was alive, he was a user of the Thunder Breathing style and a former senior disciple along with Zenitsu under the former Thunder Hashira.
However, while Zenitsu was undergoing Hashira training and on his way to surpassing Kaiaku, Kaiaku had the grave misfortune of running into Upper Moon number one, Kokushibo. In the face of such overwhelming power, Kaiaku gave up the fight and became a demon by ingesting the blood that was offered to him. This moment starkly contrasts with characters like Rengoku and Giyu, who outright refused to become demons.
Despite his arrogant and super-confident outward appearance, Kaiaku was just as much of a coward as Zenitsu appeared to be early in the series. The difference between the two is that Kaiaku was able to hide his cowardice better. Before he became a Demon Slayer, Kaiaku survived by any means necessary, including stealing and sacrificing others for his survival.
Kaiaku’s actions embody the dark truth of human nature: when choosing between others and one’s own well-being, many will choose self-preservation. This is why society praises those willing to put others before themselves. Despite being a natural with the sword and the best student of his master, Kaiaku’s fatal flaw was his inability to move past his self-centeredness.
When he battles Zenitsu, the contrast between them becomes clear. Zenitsu’s fear never stopped him from doing the right thing, training to grow stronger, and acknowledging the risks he undertakes. Their battle is a display of conflicting values of right versus wrong in self-preservation. Zenitsu’s defeat of Kaiaku is rewarding for both their character arcs: Zenitsu is rewarded for his bravery, while Kaiaku is punished for giving in to his fears and the blood on his hands.
Kaiaku’s Thunder Breathing made him a deadly Upper Moon, capable with the sword and possessing high agility, quick slashes, and bursts of speed. His biggest drawback was never learning the first form of Thunder Breathing, despite mastering the other five forms. His Blood Demon Art, electrokinesis, allows him to create black lightning that can attack enemies. During his fight with Zenitsu, he nearly killed him with his Blood Demon Art after almost destroying his eyes and leaving him severely injured.
