In “Demon Slayer,” We know Muzan can turn people into demons by giving them his blood. But when Muzan attacks Tanjiro’s family, why does he only turn Nezuko into a demon? if Muzan wanted to make more demons, why not turn the whole family? Does he purposely make her a demon? There are a lot of questions you might be thinking about.
When Muzan attacked Nezuko’s family, the Kamados, he killed everyone except Nezuko. Muzan was trying to make a demon that could go out in the sun without dying. He might have his blood to all the Kamados, but only Nezuko survived. Muzan thought Nezuko would die like the others, so he left. But Nezuko didn’t die. She became a demon, but a really unique one.
Not every human can survive the transformation process. It’s likely that Nezuko was the only one who survived after being injected with Muzan’s blood, either due to her innate physical or spiritual compatibility.
In Demon Slayer season 3, we see Nezuko able to survive in sunlight. She could go out in the sun without getting burned. Muzan had been in search of someone like her for years. That’s why he gave his blood to a lot of people to see if they’d turn into demons and survive in sunlight. But No one survived in the sun except Nezuko. I can say, She’s special. She doesn’t eat humans like other demons. Instead, she protects them with her brother Tanjiro. She’s different than other demons.
Conclusion
Muzan did not intentionally choose Nezuko, at that time he didn’t even know she would be the one to survive in sunlight. He might give everyone his blood to turn them into demons in Tanjiro’s family. But Nezuko is the only one who survived.