As one of the strongest demons that appear in Demon Slayer, Kokushibo is well-known. He remains mysterious even though a great deal is known about him. Kokushibo is considered as one of the one of the oldest demons that exist and he has fought a lot of battles as well. He won most of the time, but he couldn’t let go of his problems from his human life, even after hundreds of years. In the end, these problems led him to become a demon and caused his defeat.
In Demon Slayer Tanjiro is a boy who trains hard to become a demon slayer so that he can find a cure for her beloved sister Nezuko, who turned into a demon herself. Tanjiro wants to turn her sister back to the human form so that she can live a normal life.
Kokushibo used to be a demon hunter hundreds of years ago. He was strong, but his twin brother was even stronger and invented a special fighting style. Kokushibo felt jealous and made his own style, but it wasn’t enough to make him feel better. This jealousy never went away, even after he turned into a demon himself.
Kokushibo trained with his younger, super-strong brother and even got a special mark that boosted his skills. But there was a catch – the mark meant he would die young. Afraid of death, Kokushibo did something shocking: he became a demon to live forever. This made him one of the very few demon hunters to switch sides! Even though he became a demon, he didn’t hurt his wife and kids.
Kokushibo got a creepy makeover after becoming a demon. He sprouted extra eyes and became way more menacing. He became one of the best swordsman as well According to himself, his techniques were so refined and legendary that they have no hopes of it being passed down for future generations. As a demon, he lived for almost 500 years and avoided the curse that would have killed him as a human. He climbed the demon ranks and became the strongest one, defeating many challengers. He even had a special ability to absorb some of these losers, which might have been his way of eating. The only challenger he spared was Akaza, because he was tough competition.
Even as a demon super strong, Kokushibo finally beat his brother. But winning wasn’t all he’d hoped. It turned out his brother dodged the death curse and lived a long life. This made Kokushibo question his choice to become a demon for immortality. The viewers don’t know for sure how much this doubt bothered him until he dies.
