here is basically what happens in the manga 4r6y3e

A girl falls in love with a boy who turns out to be her half brother. Shit happens and she ends up falling in to water and wisked away to another world. She was also very good at kendo i believe, anyway when she come to this world she gets a bounty put on her head due to a prophecy and shit.

This is all i can . Please help me find it. Thank you

sounds like Saver... but its a manhwa

"The Cinderella witch does not use her magic on herself because she knows the emptiness that follows when the spell breaks"

Yup, it's Saver.