A character on a flat, walkable Rooftop, such as a School rooftop. See On Roof for characters on angled, non-walkable rooftops, such as the roof of a House or Pagoda.
Flat Rooftops are common on many Japanese Schools, certain styles of Apartment blocks, and high-rise Buildings with rooftop pools, gardens, lounges, etc. These rooftops usually have Fences, Parapets, or Railings to prevent people from falling off.