Samurais are gaining popularity over Japan.  A documentary crew is interviewing some of them including Bokuden-chan, the strongest swordsman, but when the film comes out.  The Samurai Girls have a new problem to deal with.
You can't let your 
guard down around her.
Es alguien de quien hay que cuidarse.
Hay que tener cuidado con ella.
Não podemos nos descuidar perto dela.