Yes, you may have the found item claimed by another person on your behalf. When the found item is collected by someone else, a Letter of Proxy, a official certificate (Japanese driver’s license, passport, insurance card, student ID card, etc.) of the mandator and the proxy (a photocopy of mandator’s official certificate is acceptable), and the proxy’s name seal (a stamp-type seal is acceptable) are required.
Note 1: A Letter of Proxy is not necessary when a family member who lives with you is picking up the found item.
Note 2: Please download and print the Letter of Proxy template from the link below.http://www.tokyometro.jp/lang_en/support/lost/pdf/ininjo.pdf