Summoning Nagato as a loli slaying beast is not a bad strategy, until one day that beast realize that you, Hibiki are a loli yourself.
Hibiki doesn't need to outrun the Nagamon (although she can easily do so), she only needs to outrun the other girls.
Nagato-sanThis is the Northern Little Sister.You called!?Be affectionate with her.I... I can be affectionate with her...!?Let go! Let go!?All right! I, Nagato, shall come with you!!