Кувабара Шідзуру

Kazuma Kuwabara's tough older sister. Like her younger brother she also has a high level of Reiki sensitivity and is extremely strong; Shizuru, in the beginning of the manga, has more of a sixth sense than her brother. Shizuru, 17 at the start of the manga, wants Kazuma to grow up and get an education so he can make something of himself. Shizuru, an aspiring beautician, gives Keiko her new haircut after Keiko rescues Yusuke from the burning house in Chapter 13: Qualifications for a Girlfriend. Shizuru is also a chain smoker and the biggest part she plays in the anime series is during the Dark Tournament (Ankoku Būtsukai) where she falls in love with Sakyo, the owner of Team Urameshi's rival team, Team Toguro.

He saves her life twice, but she is unaware of his true identity until the end. She also knows Yukina's connection to Hiei because she saw a videotape that provided the details for the mission that Yusuke and Kuwabara had to rescue Yukina from Gonzo Tarukane (only she, Botan, and Yusuke saw the details that Yukina is Hiei's sister). Like Keiko, she is a woman who is unafraid to speak her mind or deliver a beat-down where needed. She even yells out to Toguro during the Dark Tournament when he goes up to face Yusuke. Shizuru also appears in the Chapter Black and Three Kings saga.

During the Three Kings saga, Shizuru who was tired of seeing her brother recklessly endanger his life began to harshly discipline Kazuma to force him to keep up in his school studies and warned him that he would only bring ruin to his life if he kept fighting. In the anime, Shizuru is introduced later (during the Yukina arc rather than right after Keiko's fiery haircut), but ends up having a larger role, mostly due to the addition of her romance with Sakyo and her taking on Atsuko's role.