Demon slayer:Do you know?

Reason of why Muzan became a demon

---- Some of you guys may don't know about this,so if you are a Demon Slayer old fan,then you can skip this.

----During the Heian era, due to his terminal illness,Muzan killed the doctor who treats him and ha found himself became a creature that is so strong but got the fearess of the sunlight.And that kind of creature is demon.His goal was to live forever without any fear of death and become eternal.

----To accomplish this goal, Muzan can make his dream come true in two ways.First is to find the blue spider lily and the second is to create more demons for hoping one day, one of them can conquer his weakness of sunlight.

Remarks: It's later revealed that Muzan got the same bloodline as the Ubuyashiki family.

where did I got the info: Kimetsu no Yaiba wiki 

website: https://kimetsu-no-yaiba.fandom.com/wiki/Muzan_Kibutsuji