This manga involved an aspect of time travel where the girl had her arm replaced by a "phone" that could call her alternate dimension self and the girl that gave the arm dies, she goes hunting to find out what happened to her. Big organization/cult was behind it and she becomes the head of said cult after like hundreds to thousands to millions of tries.
Thats the only one I remember thats a bit like that- there's deffinatley a witch who lives in a town at the start and people are afraid of her, and she contains demon spirits that give her her power but are also bad for her.. If it's not that one then I'm tapped on webcomics.