Interview and Written for PhD in Osaka University, Department of Physics

For applying to the PhD program in Physics (for international students), we need a conditional acceptance letter from a faculty member of the department. I emailed a research group for the same, and they have decided to take an interview for one hour (20 minutes presentation included) followed by a written examination for 3 hours.
I would like to know what should I expect from such a selection procedure. Moreover, this is just a pre-selection process, after the conditional acceptance letter, I would be able to give the actual entrance to the PhD program.
Any tips would be beneficiary.