Warning: Hunter x Hunter spoilers ahead.
The anime Hunter x Hunter isn’t too scary, unless small children fighting grown men for a living frightens you. But there is one aspect to the show that is pretty creepy. In this show, we follow a kid named Gon Freecss who is on a journey to find his father. Early in the series, he makes a friend named Killua Zoldyck. But much later on, you find out that Killua has a sister.
Killua’s sister, Alluka, is possessed by a dark being named Nanika. They seem to coexist in Alluka’s body peacefully unlike the relationship between Yuji and Sukuna. When Alluka asks for three things in a row and gets what she wants, Nanika comes out. Alluka only comes back when Nanika grants a wish for the person who helped Alluka. When the wish is granted, people die. When Alluka’s requests are refused, people die.
You can watch this one on Hulu, Netflix, Funimation, HBO Max, and Crunchyroll.