Ashi Girl (2017)

Yui Hayakawa is a 16 year-old night school student whose only strong point is her ability to run fast. She accidentally goes back in time to the Warring States era of Japan where she makes use of her ability on the battlefield to protect her beloved young lord Tadakiyo Hagi (Kentaro). Through finding a goal to work towards, Yui finds a new world waiting for her as she uses her power to change the person she loves and create a better future for the people she meets. Based on the the manga - Ashi Gaaru