how did muzan turn into a demon

No, Izuku doesn't turn into a demon in the manga. It's not part of the original storyline.

No, Deku doesn't turn into a demon in the manga.

The reason why Li Bing turned into a cat demon was still unclear. In the series, Li Bing's transformation might be related to some kind of drug or experiment, but this was only speculation. The specific plot still needed to be interpreted. However, Li Bing's special ability and the empress's trust in him indicated that he had superpowers and was stronger than Di Renjie. In short, there was no definite answer to the question of why Li Bing became a Catwoman.

They could interact in a very confrontational way. Michael Jackson, with his kind heart, would likely be appalled by Muzan's evil deeds. He might use his music as a weapon to try and drive Muzan away or at least make him see the error of his ways.

Muzan was ultimately defeated by the collective efforts of Tanjiro, Nezuko, and the other demon slayers. Their teamwork and perseverance were key to ending Muzan's reign of terror in the manga.

Tanjiro Kamado and his allies managed to defeat Muzan. Their combined efforts and determination were crucial in the final battle.

Yes, Muzan does die in the manga.

Camilla had turned black during her relationship with Ultraman Diga. Camilla was Ultraman Diga's lover, but because of love, she eventually fell into darkness and became a dark giant. Diga seized the power of Camilla and the other two dark giants and sealed them. When the seal was lifted, Camilla turned dark. Before the Dark State, Camilla was a righteous giant of light, but due to the darkness in her heart, she had fallen into a dark giant. The turning point of her blackening was in the battle with the evil forces. Her power was eroded by the evil forces and she gradually lost herself, becoming cold and heartless. She only had one goal, and that was to destroy all evil beings.

The reason why Camilla turned dark was because of the love-hate relationship between her and Diga. Camilla was Diga's lover 30 million years ago. She was originally a righteous giant of light. However, due to the darkness in his heart, he had fallen into a dark giant. Diga seized the power of Camilla and the other two dark giants and sealed them. When the seal was lifted, Camilla turned dark. Although the specific process and reason of the dark side was not explained in detail, it could be speculated that Camilla's dark side was related to her love and hate for Diga.

Well, one theory is that a genetic mutation occurred within the crow population, leading to the black coloration. This mutation might have provided some advantage, causing it to become more common over generations.