Ninja to Koroshiya no Futarigurashi

On the way home from school one day, Konoha Koga rescues Satoko Kusagakure, a ninja who escaped her village. Soon, pursuers from the village show up in search of Satoko only to be deftly dealt with by Konoha. As it turns out, the unassuming high schooler is actually an assassin. Thus, the potentially cutthroat cohabitation of a ninja and an assassin begins!

(Source: Crunchyroll)