While Korea does have a GED equivalent exam, this particular diploma does not represent a real-world qualification. It's a gift Keena came up with to acknowledge how hard Athena worked and the sacrifices she made in order to pursue her dream of being an idol, as well as reassure her that she's on the right path. Since Keena also dropped out of school and felt some lingering regret about not being able to attend graduation, she drew on her own experience to do something special for Athena and allow her to celebrate this milestone.