In the university of Tokyo, some students belong to multiple faculties or graduate schools, and so they are assigned multiple student ID numbers in accordance with this※.
However, only one student ID number can be registered on an ITC-LMS account, and so the number displayed on your ITC-LMS account may not match with the number displayed on your UTAS account. For students belonging to multiple faculties/graduate schools, the ID number displayed by ITC-LMS may switch back-and-forth during their period of enrollment.
If your account is displaying a student number that seems unfamiliar, please reference your UTokyo Account number.
※For example, undergraduate students enrolled in the III's Undergraduate Research Student Program will have 2 student numbers (the first two digits of their Student ID number should be 5A).