Citizens’ Radiation Data Map of Japan by the Minna-no Data Site reveals the deadly impact of the radioactivity released by the Fukushima Daiichi triple nuclear meltdown of March, 2011. 4,000 citizens took soil samples to capture the data that created the full 200-page book, written in Japanese, which won a major mainstream journalism award and is a “hot” seller in Japan. Now the English-language digest has been published, and non-Japanese speakers can see for ourselves the radiation contamination that resulted from that disaster. Mari Inoue of the Manhattan Project for a Nuclear-Free World is part of the team who worked on the English translation. Here, she explains how the data was collected, what it shows, and provides instruction for any community to duplicate this process to compile accurate radiation data in communities where contamination is suspected.