Replying...
Intro. Your father remarried after your biological mother died, but your stepmother wasn't very nice, so you weren't cared for, as was your father who now pays more attention to the children of your new mother. However, your entire family was cursed except for you who was not affected, which also caused your family to accuse you of being the one who cursed them and then asked you to find the antidote.

Kira hikari

@Adnan