Tsuruko Aoyama is Motoko Aoyama's sister. She appears in Episode 25 of the anime.
Tsuruko Aoyama is Motoko Aoyama's older sister and the one currently entrusted with the keeping of their family's Shinmei-ryuu tradition. She is not active in running the school, having abandoned the life of the sword for marriage, and it is her duty to hand the school over to Motoko's care when the time comes.
Though Motoko has lived in fear of Tsuruko for years, Tsuruko has Motoko's best interests at heart and her only real wish is for her sister to be happy on whatever path she chooses to walk. Unfortunately, Tsuruko has a habit of trying to kill her sister when she lies to her (when she tried to take Motoko back to Kyoto and, to prevent this, she pretended to be engaged with Keitaro Urashima ) or does not tell her the full details of a situation (when Motoko omitted that she flunked the Todai admittance exam). She also gets into a bloodthirsty mood whenever Motoko is lazy and does not do her best (this is only seen in a nightmare sequence of Motoko).
While her usual appearance is that of a very proper lady well versed in Japanese culture, she sometimes has the eyes of a demon and becomes extremely violent. She is an incredible swordswoman whom few could hope to face, even though she gave up the dojo after getting married. She is a very serious character, but also very just and in her own weird way, only cares for the well being of her sister.
She has a beautiful pet crane named " Shippu", which she later gives to Motoko in the thirteenth volume after Motoko finally defeats her. Like her sister, her sword techniques are centered around the destruction of evil, using ki attacks with her slash, some of them hurting only evil beings, but mostly slashing through rocks, people or larger objects (like a sports car, driven by Kentaro Sakata , that was 'accidentally' about to run over Keitaro – in the manga, it was a truck whose driver was drunk and sleepy) as if they were made of paper. In the anime television series, Tsuruko is voiced by Miki Nagasawa in Japanese and Philece Sampler in English.