Satoshi & Shion

Shion is the older (believed to be younger par everyone but the twins themselves) twin sister of the Sonozaki twins. She was sent to St. Lucia's Boarding School, but escaped with the help of Kasai Tatsuyoshi, a man who acts like a bodyguard to the Sonozaki family.
Shion is the main villain in Meakashi-hen, which appears to be Watanagashi-hen from her perspective (though certain differing events mean the two are truly separate arcs) and shows that she was the main villain in Watanagashi-hen as well. She despised Hōjō Satoko in Meakashi-hen, blaming her for Satoshi's suffering, but in the arcs...