Satsuki Tsukino(月野五月; Tsukino Satsuki), is the eldest daughter of the Tsukino Household and a supporting character in Highschool DxD: Яe-birth, being also the main antagonist of Yoko's side through volume 8. She's a doctor of Kuoh city clinics, a former student of Kuoh academy and Ichijou Tsukino eldest half-sister. Due to her name, she's usually referred as "Gou-nee"(ゴウ姉; "Go-nee") by her younger siblings and friends.