How can I request Japan Post to hold my letter for more than a week?

I am currently away from Japan for a few weeks, and it seems that I will miss a particular letter that is being sent to me.

From what I can understand, they seem to store it for 7 days by default. But I will not be returning before 3 weeks.

Is there a way (preferably an online form) I can ask them to hold the letter for longer?

This is also a mail which they need me to show an ID to receive.