Talk:Maria-sama ga Miteru:Format
In the world of the Lillian Academy, Onee-sama has a specific usage.
Unlike normal schools, where you would refer to older girls you know as Onee-sama and use name-sama for closer acquaintances; within Lillian, the opposite is true.
For distant acquaintances, you use name-sama (or San as necessary) in normal use. When addressing the Roses or their boutons, you would use Rosa Chinensis, Gigantea, or Foetida (en bouton) respectively. Typically, only petite-sœurs would use Onee-sama (think of it as a title), and then only with their grande-sœur. An exception to this would be when affectionately referring to the Roses, because they're seen as guiding the underclassmen. Suffice to say, "Onee-sama" carries a respectable amount of weight.
This is why Yumi always refers to Sachiko as Onee-sama, while everyone else in her year calls her Sachiko-sama or Rosa Chinensis (en bouton). Early on in their sœur relationship, Yumi uses Sachiko-sama, and is eventually told: "From now on, if you call me 'Sachiko-sama,' I won't reply."
Hope that clears up any misunderstanding.
JBV^_^