The Master's Keep is the area where the Lecarde sisters, Stella and Loretta, await the heroes' arrival. After curing them from their vampirism, a gallery full of paintings lies (must heal them with Sanctuary or they will die and the bad ending will outcome). The paintings are copies of the original areas, although turned around or upside down. The duo can enter Brauner's Lost Gallery after defeating the bosses in them. Then they can enter The Throne Room after defeating Brauner.
After Brauner's defeat, the player will enter a painting that leads back to the castle, specifically The Throne Room. The painting containing the Lost Gallery will have burned and the area will be inaccessible afterward. Due to how small the area is, it is often counted as a separate part of the Master's Keep.