The loan period (return deadline) can be renewed (extended) except for some materials, which are reserved or in a laboratory, etc.
You can do the renewal procedure on the usage confirmation page of OPAC or at the counter in the library.
Nagoya University Library Search (OPAC): https://opac.nul.nagoya-u.ac.jp/?lang=english
For details on how to read the screen, check the guide sheet "6-1 Confirm status / Renew due date ".
https://www.nul.nagoya-u.ac.jp/guide/gsheets/index_e.html