The Hollow Queen is the second stratum boss in Etrian Odyssey IV and is the source of all Hollows. However, defeating her does not prevent you from encountering Hollows again. The Hollow Queen is encountered at the end of the Misty Ravine and is the boss of the area, where she is guarding the Medium. A battle automatically ensues when she is approached. Her battle theme is called The Burning Crimson Sword Dances, the theme of all boss battles.