Cedric_7512
Bro according to you mc is a shikigami and their work is to clean or purify corrupted soul's / hollows from the world and send them to afterlife so you can add different horror movies stories in fanfiction like: The Conjuring, Halloween, INSIDIOUS, Annabell , IT AND ETC . This type stories only effects small number of people so it will not affect plot of the MCU.
I like Yao but can you change the appearance of this one please don't let her appearance bother me but Yao of the MCU seems quite old in all honesty so I can't imagine her being in a relationship where at least try to rejuvenate her or change her look otherwise Natasha also seems to be a good idea but I have no more opinion about her