Hitokiri Shoujo Koushaku Reijou no Goei ni Naru

Shurine, a girl raised for the sole purpose of becoming a bodyguard, is framed by the state and branded a "hitokiri".

Following a life on the run, she meets Lutecia, a duke's daughter, aboard a magical train. With Lutecia's life in danger, Shurine offers a solution:

"If you need a bodyguard, why not hire me right now?"