In the Before Arrival Checklist there is information about having a guarantor in Japan (Yamada Jun). Can I use this name as my guarantor for apartment rental companies?

No, you cannot put Mr. Yamada Jun as a guarantor for your accommodation.
He is a guarantor only for your visa application.
If you couldn't find an answer to your question or concern,
-For enrolled students: you can inquire us through the Scomb we shared when sending you the Before Arrival Guideline.
-For prospective students: you can inquire from
here.