Location from Sailor Moon by Naoko Takeuchi / Toei Animation
An elite private school in the Sankakusu district — 60 floors, a full curriculum from preschool to graduate level, and the secret headquarters of the Death Busters in the basement.
Mugen Academy is both a real school and an elaborate operation. Students like Haruka, Michiru, and Hotaru attend legitimately; underneath, the Death Busters collect Pure Hearts and prepare for the Silence. Kaolinite runs it administratively. The Witches 5 work as section teachers. It was built in a location chosen specifically because it exists at an intersection where the Death Busters could infiltrate Earth without triggering Sailor Uranus and Neptune's detection abilities. This turned out to be wrong, but it bought them a full season.
An imposing modern structure that towers above the surrounding area — deliberately placed in a spatial flux zone the Death Busters call the Omega Area. Gleaming and institutional, with advanced facilities visible through the windows. Professor Tomoe's laboratory is behind the main building. The building is eventually destroyed when Pharaoh 90 arrives.