The war has subsided and the female protagonist has returned to her country to go to school. The youngest S-class Alpha Colonel is the male protagonist, a young master from a nouveau riche. His mother's family is from an artistic family. The second heroine, an S-class Omega, is under the command of an S-class Alpha captain, and she is her childhood sweetheart with the second heroine (well, it's not like they've known each other since childhood anyway).
The second male lead, the eldest son of a declining family, the youngest president of an international company, S-class Beta
Idea: A sudden whim?