The demon of the future (KNY X F! BNHA! Reader)

"It doesn't matter what timeline I'm in, I'll be a hero that will save people as much as I can!" Ubuyashiki (Y/n), the great-granddaughter of Ubuyashiki Kiriya with a demon quirk got sent back in time by a time villain, to when demons still exist. How will she get back? What will she do about the man-eating monsters t...