Last Sister Class (2020)

Lim Da-young, an older sister who intercepted her younger brother's lover. Because of that, he confines his younger brother Da-jung Lim in a mental hospital and leads a happy marriage with Yoon Tae-jin. Then one day, the younger brother escapes from the mental hospital and conspires with the helper Jo Yong-hwan, who was a friend of the ward, and a desperate revenge for the older sister and former lover (Yoon Tae-jin) unfolds. Da-young's bloody kidnapping, their tamed slave life, and enduring harsh punishment.