The Second Night - S3.E2

Despite her shocking revelation, Ruri is ignored by Hayate and the others until she is finally brought before Nagi who hears from her that she is actually her sister, despite having no proof of it. Nagi allows her stay for a while, but after seeing her snooping around the mansion, she decides to take her to live with the other tenants of the Violet Mansion. Ruri refuses to stay, until Nagi is convinced to give her a chance. Nagi asks Ruri if she has any sort of special skill and she reveals herself as a master of Systema, strong enough to confront Hayate. Hayate is attacked mercilessly by her until he decides to fight back and she starts crying, which is later revealed as just a trick for him to open his guard. Nagi reprimands Ruri for using such underhanded tactics but compliments her for her fighting skill, even asking to learn it from her.