A group of kids come across a Geiger counter kit in Akihabara one day. What they find connects to a sodium leak incident at the Monju nuclear power facility. The children share an attitude of being willing to do anything and go anywhere, and they are ready to give whatever comes their way a try. Adapted from Saibara Rieko's manga, the ten-episode ONA was distributed on the Tate Anime smartphone app as one of eight titles, with its first episode released early before regular distribution began in July 2017.