graduate student; postgraduate student
Refers to a student enrolled in a graduate school (大学院), typically pursuing a master's or doctoral degree. Neutral term used in academic and everyday contexts.
He is researching physics as a graduate student.
Once you become a graduate student, you end up spending a lot of time on research.
He is a graduate student at the University of Tokyo.
She plans to become a graduate student next year.
I'm devoting myself to research as a graduate student.