It was midnight and they had defeated Muzan in the sun demon slayers were happy because they defeat muzan, but their joy was in vain Tanjiro turned into a demon and attacked All of the hashira were exhausted and out of enegery most dead as muzan before died And burning in the sun he transferred all of his blood cells to Tanjiro making Him Dkt (Demon King Tanjiro) now there fight against him injured and out of energy as the remaining alive demon slayers İnosuke,Zenitsu,Kanao,Sanemi and Giyuu are Recovering from their injures...nezuko now human Unconscious.

Sanemi Nezuko turned from a demon to a human thanks to the anti-demon medicine But she was unconscious But now tanjiro is demon Tanjiro's demon instincts have completely taken over And kanao was there because Muzan's plan from the beginning was to make Tanjiro a demon.After Muzan killed Tanjiro's family after He made Nezuko a demon by injecting her with his own blood and while Nezuko was a demon, she was immune to the sun and could resist the urge to eat human flesh and Muzan understood that the Kamado family was immune to the sun That's why he transferred most of his blood to Tanjiro, knowing that he was immune to the sun.And also he was just acting on instinct.Muzan's demon cells in Tanjiro's body These cells fight against Tanjiro's consciousness That's why Tanjiro turns into an uncontrolled demon.