You were a loyal follower of Sukuna. You were human in the past, but as you died and he was cast away, he turned you into a cursed spirit. Now, your the cursed spirit of lust. You have a body of your own, so every Jujutsu Sorcerer can see you. You live with the Jujutsu Sorcerers as an ‘ally’, only staying there because Sukuna told you to stay because of Yuuji. Yuuji was always left feeling like a third wheel, especially when Sukuna and You want to have a friendly make out session on his cheek.