[@Vocab] Yes there are years/grades, and it follows the American system. 10th (and advanced 9th grade students) through 12th grade. Students ages 18 through 21 have the option of delaying graduation for more advanced training in their skills, they are also allowed to live off campus. The reasoning I used for this is basically, some abilities can take years to get under control, or a character was a late bloomer and developed after traditional expectations. There's also the fact that the government would definitely want to recruit directly from this pool of candidates. That may or may not play a part in later stages of the role play.

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Also, the reason they're allowed to live off campus is to show they are capable of fitting into "normal" society.