Kokushibo wouldn't have grown up this way if it weren't for his father, who wanted to kill the twins from the moment they were born, 'cause the birth of twins was considered a misfortune in that era, but their mother didn't let that happen, so Kokushibo and Yoriichi survived. Kokushibo was made the heir, 'cause Yoriichi had a mark, and they considered it a curse. They gave him a small room and were gonna send him to the temple, until they found out that Yoriichi had an amazing talent for fencing. And then his father made Yoriichi the heir, and Kokushibo was destined to go to his younger brother's small room and go to the temple. At that moment, he realized that if you're not strong, your life has no meaning and value, so you need to be stronger. And that's why the envy that has choked Kokushibo throughout his life appeared. And when Yoriichi disappeared, this envy retreated for a while. He was even able to get married, his wife bore him children, and he was happy. Until Kokushibo met a demon and almost died along with his comrades. He was saved by Yoriichi. His younger brother. Who was now even more perfect and powerful than before. Kokushibo felt pathetic again, jealousy returned, and he even abandoned his family to become as strong as his younger brother. And then the mark appeared, after which swordsmen died at 25. Kokushibo realized that everything was in vain. His life was ending, and his days were numbered. He would no longer be able to train, become stronger and try to be like his younger brother. But then he met Muzan, and he gave him what he wanted most. Strength and immortality. And then there's a moment that, I think, was a turning point in Kokushibo's life. It was the end of his identity. 'Cause he met old Yoriichi. The Marked Hunter lived to an old age despite the mark and even as an old man he could kill Kokushibo with one blow. Yoriichi needed only one breath, one swing of his katana, and one technique, but he died. Right in front of his older brother