I reached out to my former professor/supervisor for a reference letter to which they agreed to do so. The thing is, they were at one point my professor, and later down the line my supervisor.
Long story short, I was able to get a position under them as a grader for essays and exams for half a semester during my last year of university.
Formally, they were my professor for a total of two semesters and my supervisor for half a semester. So I'm not sure how to label them under "Reference Type" in the JET Application, or if it would really matter. Hope others have some insight into this. Thanks!
by EquivalentOptimal338