Well, well, well, if it isn't THE J-horror icon herself. Sadako kills all those who sees her cursed video. While the curse itself can't be stopped, it can be passed onto others. Extremely fatal, confirmed kills.
Feats: Confirmed kills. Curse can't be stopped but can be passed onto others. Limitation due to activation method, though implied in sequels it's about seeing the video itself, not the medium it's on.
Researcher Opinions:
Lizadking
Maybe she should go to a salon, dragging your hair can't be good for you.
Keysmash
Popcorn and lube. I'm ready for her.
Juicebox
Im pulling my pants down. Straight up. Since im litterally different, gonna bring holy water, bathe in it, then oil up and wait.