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This boy was brought into the animé of "Demon Slayer". Originally, he's a demon killer and, along with Zenitsu his brother. He fell under the influence of his own temptations one day and became an evil spirit.
The rank of "Upper Rank Six" in the Twelve Kizuki, a designation that emphasized his powerful abilities. What is most interesting of all is how he went from a hesitant human to an evil demon, with an aspect of betrayal, hatred and ambition.
For example Kaigaku is not a usual sort of person. This guy is in the popular anime 'Demon Slayer'. With his adoptive little brother Zenitsu, he used to be a demon hunter - but Lord! When he turns into a demon one of them dies. He is promoted Upper Rank from Twelve Kizuki - quite a significant promotion! And this guy went through breech, gall and lean in the year he held power.
Kaigaku is a character from 'Demon Slayer' who went from Demon Slayer to a demon, achieving the 'Upper Rank Six' title in the Twelve Kizuki.
Oh, Kaigaku! He's from the 'Demon Slayer' anime. Started out as one of the good guys, a Demon Slayer, even teamed up with Zenitsu, his brother. But plot twist! He becomes a demon himself and rises as the 'Upper Rank Six' in Twelve Kizuki. His story's pretty wild, full of bitterness, and a thirst for power.