Import customs returned my parcel to Japan, friend who shipped it isnt in japan anymore

I need help: My friend recently shipped a parcel with some clothes she got in Japan for me. It was in customs for 5 days, now the German customs decided to return it to the sender, she probably made a few mistakes declaring its value.
The real problem is, that she isnt in Tokyo anymore, so theres no one to accept the parcel. I would have to get it to another address delivered, I shipped with Japan Post.
Any tips?

by Patient-Mango4347