Okay, new yandere story idea.
Inspired by the stories of the perfect demon, a scientist tries to create his own version of them. One that wouldn't need human flesh to survive, that could walk in sunlight. However, others didn't approve of this idea as they didn't want history to repeat itself. So, he did it in secret and used his first born daughter as his test subject. A perfect demon. So, how will the history change when the perfect demon and her baby sister end up in the Taisho Era, where demons roam and Demon slayers kill them?