If you have any questions about multi-factor authentication, please check the following page.
https://it.support.ritsumei.ac.jp/hc/ja/sections/900002117663
RU has implemented the multi-factor authentication and mandated to enhance security. You may change your phone number along with your travel. To keep your access to RU secured webpages and receive emails, please make sure to confirm the following page for your preparation. https://it.support.ritsumei.ac.jp/hc/ja/articles/900006776543