so Mitsuba's "curse" works independently as her shadow without FMC knowing to help creating "their" story ?
since seems like all of them are mitsuba.(from their model and the "we" at beginning) My guess is forbidden art bought lots of girl soul in place of original mitsuba and all of them accept willingly to be mitsuba or simply got washed their previous identity like FMC into mitsuba's soul ?
since FMC's past memories are all gone. what's left is her past knowledge and her identity as mitsuba. The plot is kinda looks interesting. It's like mary sue tier with some mystery and horror as another layer (since her "curse" will do lots of works behind scene to push their story)