You can get the Factory Image of Galaxy Nexus.
Google Support for Nexus Phones and Flagship Devices.
http://code.google.com/intl/ja/android/nexus/images.html
Example of 4.0.4 (IMM76D) maguro
wget https://dl.google.com/dl/android/aosp/yakju-imm76d-factory-c6e807a1.tgz tar xvf ./yakju-imm76d-factory-c6e807a1.tgz cd yakju-icl53f ./flash-all.sh
