How quick people are to remember the 15 but forget the 200 in regards to her age.
She's 200, she has been alive since before the heroes great grandparents.
She LOOKS LIKE she's 15 by human standards, people are too quick to scream pedo they are forgetting key information.
Would any of you care if the genders were reversed? What if the demon lord was a 200 year old shota who looked 15 and the hero was a 19 year old onee-san?