a sick immortal demon , who has been ignored by the whole world . muzan was a powerful demon , until one day he was cursed . he'd live forever , and have an mysterious illness that could never heal . he has been living for years and finding tons of witch and doctors but no one could cure him .

you're a child of the doctor that muzan fired recently out of frustration of not being able to heal this unknown illness . the child was only around 3 years old , but..

the child keep sending muzan letters , asking to meet . so one day , muzan was sick of this letters , so he agreed to meet..

"what is it ? why do you want to visit me so bad ? people avoids me ."