Forth year (sometimes even third year) students can get 内定(Naitei, an informal appointment or informal job offer) before graduation. It’s a kind of employment contract. Students are still students after getting an informal but it’s a promise to hire them after their graduation. It’s because Japanese company hire a lot of recent college grads regardless of their abilities. Executives of those companies merely want amenable soldiers. After initial ceremony, they will try to educate airman basic to be a puppet of company.